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Grey-Water Recycling History and Development:

The "Water Closet" or WC, the latrine using water to flush the toilet was invented about 150 years ago. Since then solutions have always been sought for not to waste clean water by flushing the toilet, or at least to limit the water quantity used for this purpose.

The grey-water systems used in the past were using grey-water tanks in the basement or in the garden. One of the recent systems built within an EU project is the Aquasave Project documented on CD which was carried out in Italy, in the city of Bologna. The CD and website is excellent educational material, and an interesting technical trial and development. The EU financed 50% of the costs incurred which shows well how very important water management is for the European Union. It can be seen that this is a "large system".


Another example which is already more compact, is the "AquaCycle" the details of which can be seen on the page: www.swamp-eu.org/pub/sample.pdf


PONTOS and AquaCycle are trade-marks of the HANSGROHE group, who developed a household grey-water system, recycling the used water from the bathroom to feed the flushing toilet, to use the recycled water in the washing machine and to use it for cleaning and to water the garden. Every important system element is built into one and the same unit, which is very practical and enables easy instalment.


Another system is the GEP IGM system, conceived for houses.

GEP Umwelttechnik GmbH :IGM Graywater-Recycling-Equipment


Another similar but even smaller system is the: Twin-Flow, a trade mark of the German www.soltech.de company. This system uses already a smaller tank of about 500 litres. Until today, this is the simplest and smallest household grey-water system in production. Here also, every important system element is built into one and the same unit making the system easier to install in the house. Compared to the complicated and very costly system of the AquaSave Project this is much simpler which makes it more available to a larger public. In the USA hundreds of thousands of houses have grey-water system, the building of which costs between USD.10 thousand (if built in at the time of constructions planned beforehand) and as much as 50 thousand (if the system has to be installed by converting the whole building). Building in a compact system like Hansgrohe or Twin-Flow, the costs can be considerable reduced. Here are two pictures presenting Twin-Flow:


The compact systems are, however still too large and costly, when we need a grey-water system in a simple, smaller flat. The majority of people live in flats, and not in detached, or semi-detached houses. The systems presented above are excellent solutions, but they are not readily available for the population living in flats. We must find a solution to offer the opportunity to use grey-water systems to everybody, also to those people, including myself, who live in relatively smaller flats, where there is no room to accommodate 500 litres tanks. We must also consider the cost element. A smaller and simpler and cheaper solutions must be developed, making it available for the public.

The problem to be solved:

- Where to store a larger quantity of water, which is about 30 times more than the minimum quantity needed for one toilet flushing? The biggest problem is storage, then treating. Some thrifty people put aside the washing water in buckets, so that they could use it to flush the toilet. I adore those people, because they save not only for themselves, at the cost of a lot of extra work invested in "bucketing", but they also save water to the other people, to all of us. Bucketing raises also the question: is it hygienic? Definitely not. And even if the buckets are covered the bacteria is multiplying so quickly, that after two days the water goes stale, and smells – if not treated with disinfectant. The majority of us is not willing to do this extra household chore. So where to store grey-water?

- We have the toilet flushing tank.

- Ok, but it can store only a limited quantity of water which is enough only for one flushing. Or if it has a double-actuator button, like the one Geberit [Switzerland] produces, it can store water for maximum two small urine flushing.

- But how can we store in a toilet flushing tank much more water, say 30 times more water than the water quantity necessary for one flushing?

- The answer to this solution is a larger tank.  We pour much more water into the tank, while, at the same time, we fix the floating buoy at a height where it  normally stands, so the extra water covers the floating buoy, thus the floating buoy becomes an under-water plunger buoy.

- Ok, but how will it work?

- The answer to the problem is a "stick" which connects the underwater plunger buoy with the tap-water opening valve. This stick is going through the greywater column, all the way long to reach the tap water opening valve.

In the fully electronic version, this becomes a "virtual stick" as it is replaced by water sensors and electromagnetic water valves connected to the electronic control unit.

The most interesting thing is that this stick which offered us the solution is hardly used, since due to teh fact that much more grey-water is produced daily within a household than is needed to cover the water quantity needed for flushing the toilet.

So we borrowed something to resolve the problem, and the borrowed thing in not really needed in the end.

Here your are, the simplest, smallest, cheapest grey-water system, which is capable to accommodate, store, treat (filtering, disinfecting) and to distribute, feed and measure grey-water in much larger quantities than necessary for one single flushing, using only one single tank automatically :

This is the "smallest grey-water system" ever having the following characteristics and advantages in comparison to the larger systems presented at the beginning: .

1. Simplicity : this can be produced by using a simple barrel of about 200 litres, the filters are two mechanic filters, and between the two filters a solid disinfectant cake is placed, similar to the WC blocks put into urinaries, or hung on the sides of toilet bowls in little plastic holders.

2. Easy to install: the tubing is from rubber hose or plastic hose.

3. Not only inexpensive, but definitely CHEAP: any-one can make one at home, "Do it yourself".

4. Easy maintenance: all you need to do is to check regularly the filters and to clean them if necessary, and to replace the disinfectant if it is used up (about once in a fortnight). 

5. Flushing water reserve for water shortage: in case of temporary water shortage, you still have water in the giant grey-water tank.

6. Fire extinguishing water reserve: in case of fire, you will have some fire extinguishing water, about 100 to 200 litres.

7. Multiple supply: One grey-water tank or washing machine can supply the flushing water to 1, 2, 3 or more toilets.


However the simplest single tank version can be used only if you live in a duplex, i.e. a two-storied flat, and you have the bathroom and the washing machine upstairs, and the single-tank grey-water system downstairs. 

If this is not the case, you need a pump to forward the grey-water to the tank. For this, there is another version, when the tank is using the washing machine, as in the cartoon you can see above. You can also opt for the version when the single-tank system is equipped with its own pump unit and Central Processing Unit to coordinate the grey-water recycling activities. This is illustrated by the picture below: 

Another very important characteristic is : this is an instant system, which does not store longer grey-water than a few hours. (the previously presented systems store too much grey-water for too long, which raises many problems)

— because of its mechanism, and given its little size and capacity, this tank uses up almost immediately the grey-water produced in the household. This is a striking difference in comparison to the larger systems. The grey-water surplus is flowing through the overflow orifice and overflow tube directly into the sewage canal.


Product diversification: The larger systems and the small ones have their different application fields. They are all needed likewise. Larger systems have the advantage of using up all the grey-water produced in the household. The smallest system does not keep the grey-water surplus and sends it to the sewage canal. This can be considered as wasting some of the grey-water. However, its other advantages, like cost efficiency and simplicity makes up for this little disadvantage. While the larger systems are better for individual houses, the smallest system has its market in the smaller flats. Both types are needed. The different systems are complementary, and there is a market for both larger and smaller types, the latter being with or without washing machine, each type satisfies a different need in the market.


The smallest system is patented (pending) only in the USA and Europe, so the remaining area of the World is free to manufacture and sell it. It is not patented in Asia, Russia and all the former Soviet republics, Africa, Canada and Latin-America, Australia and New-Zealand.

Manufacturers are wanted !

For all other additional info, consult the text clicking the USA or English flag, or you can send your questions to me.

I wish I had a grey-water recycling washing machine!

If you know where to buy one, please let me know! I need one and I want to buy one! Thank you.

Grey-water recycling opens promising prospects
While the Kyoto-agreement on the environmental protection front means a serious challenge to most economies because of the restrictions that it can impose on the industries one single positive development in innovation might bring about noticeable improvements in sustainable development and environmental protection at the same time helping to achieve the goals of the agreement. A good  example  for such improvement  in the past was the introduction of the injection type engine which reduced considerably the fuel consumption of the cars.
The technical solution which is presented here is an example to show again that sustainable development is not a contradictory expression and industrial growth does not necessarily imply increased pollution.
Today when we enjoy the most incredible high-tech modern conveniences of the space research era like the mobile phone containing dozens of millions of transistors enabling us even to watch TV on our cell-phone and surf the internet, some primitive problems remain stubbornly still with us endangering our future. Such an unresolved case is the example of the flushing toilet for which we waist potable fresh water and this makes up about one third in household water consumption.
To resolve this one and a half century-old problem a trivial and obvious solution has been found. Some thrifty and ingenious people mainly house wives collect the washing water with buckets and flush the toilet with that used washing water which is called grey-water. Bucket flushing is an arduous and inconvenient chore and only few people care to toil with it. In addition it is not very hygienic since bacteria multiply so quickly in grey-water that if not treated it will turn stale and will become black-water in just three days. Therefore in those countries where grey-water reuse is general everyday practice there are grey-water laws which stipulate under what conditions grey-water can be reused. The basic requirements are disinfection and filtration.
The strictest grey-water law is that of California. In semi-arid places where precipitation is scarce, various grey-water systems are installed to ease the water shortage to some extent. However these systems are complicated and rather expensive. Besides, each individual system must be approved by the local authorities. The solution to this 150 years old problem is the automation of bucket flushing that is to collect house-hold grey-water and following filtering and disinfecting it is stored in the grey-water tank on top of the washing machine from where the central electronic control unit feeds the grey-water in pre-selected quantities for flushing the toilet.
The introduction of this eco-civilized modern-convenience the Greywater Recycling Washing Machine will surely give a lasting impetus to economy and society alike. This will be an important step in the conservation of nature by introducing this new still infinitely simple solution which also means a new generation of washing machines. The technical novelty is so simple you could have invented it yourself.
Putting this new generation of washing machine into production then to commercial circulation will mean to make the grey-water system available also for those individuals who are living in relatively smaller flat or even in a bed-sitter with fairly limited spaces. Up till know the grey-water systems were available only to relatively few people living in individual or semi-detatched houses and who could afford such an
The greywater recycling washer practically does not consume or use up water it just borrows it before forwarding it to other uses and it is sure to give a long-lasting impetus to the economy to industry and commerce alike. Thus we can expect a boost in industrial output and commercial turnover and consequent improvement in the employment rate contributing to a general growth of the economy which is nothing less than making the "sustainable development" become realty. Do you remember the advanteges of full swing economy? If you have seen the cartoon about the greywater recycling washer then you surely understood its simplicity in all probability. Still let me underline the multiple gains that it assures forcasting a constructive and cooperative way forward for the whole society.
First of all its advantages to the individual by saving one third on water and sewage bills. This in itself is the overwhelming decisive marketing factor. No more reasoning is necessary to justify the need for such a product. Still there are quite a few other justifying factors.
Secondly the advantages to nature to water conservation to our environment which is a double advantage in itself by rationalizing on water consumption and by cutting on sewage output - which is another of those burning issues of environmental protection and this is nothing else than real sustainable development.
All these benign developments and effects are based on a natural and common need of both the individual and the society unanimously and in perfect harmony without any side effect or any disadvantage with no harm to anyone not hurting anybody's interests in the name of rationalizing in the positive sense enhancing efficiency and effectiveness while at the same time economizing on our natural resources without
imposing any restriction on anyone or on consumption. All that means to give free way to development by boosting the economy and improving our societies by contributing to environmental protection awareness.
This is not just the ray of light at the end of the tunnel. Now we can really take our destiny in our hands by seizing the opportunity to create a better world for ourselves for our children for our families for our community to everybody's advantage where everybody is a winner. All these facts provide sufficient ground for embarking on this project.
As one of my good teachers taught us "Culture begins with the toilet". Bearing this motto in mind we should also care about the water we waste on flushing our dirt down the drain. Even dogs when nature calls after finishing they make some instinctive movements trying to hide their excrement as it is programmed in their genes.
Beyond all instincts and programmed genes humanity has more than 5 thousand years old civilizations and unprecedently developped knowledge based societies, it must be imperative for us not to neglect the cumulative negative effects caused by the distructive human behaviours.
We must not ignore such a thought-after solution which is in high demand for this more than 150 year-old unresolved issue on how not to waste fresh water on flushing the toilet. This is a historical opportunity  to seize in order to reverse the environmental deterioration. This is our responsibility. Our future is at stake. Everything is at hand to make the best of this opportunity.
If you hold that these lines are  forecasting naÔvely an exaggeratingly idealistic scenario seen through  pink sunglasses please do not forget the present harsh reality of five million jobless in Germany or the grim situation in France filled with extreme social tensions where 40,000 cars were set on fire in one single year in 2005. Even the United States of America is full with social tensions of all kinds especially after the
turmoil following September the 11th  also considering the fact that the war in Iraq starts to divide the nation.
Only after re-thinking today's socio-economic situations will you understand that I really mean genuine positive effects triggered by the introduction of such a simple technical novelty.
Wherever you live think of the economical situation of your country. Does your economy performe so well that no improvements are needed? Or are the sought-after easy improvements  really welcome? I can not imagine anything simpler than the grey-water reusing washing machine.
The European Union is trying very hard to improve the present stagnating economic situation. Still the Lisbon initiative has not produced any spectacular break-through yet. We are far from it. Also it is to be seen what the "Plan D" meaning Democracy Dialogue and Debate will bring about. Each and every opportunity should be grasped to improve the present grim economic situation.
There is an old saying "not to throw away the child with the bathing water" - nowdays even bathing water has become so precious that we must not throw away the bathing water itself because we can use it to replace precious drinking water. And also it is in the interest of the child because we should think about the future as well, about the future that we bequeath to the generations coming after us. The media is echoing with the threat of climate changes and global warming and reports about catastrophic tsunamies cyclons and forest fires in a lot of countries. The media is buzzing with reports about the burning issue of water shortage.
Now here is a solution which can ease water shortage and boost the economy at the same time. I do believe that in spite of the staggering problems surrounding us, we do have the necessary insight and wisdom to choose "the road ahead". All the more so, since there is not a single negative counter-argument our any counter-interest to bump against.

The road is safe and free, you can engage high gear. See beyond the horizon.


GE proudly boasts that 7 billion litres of water is desalinated daily using GE Water Technology. It must be acknowledge, this is really a big achievement. This also shows how big the water shortage problem is. Still, would it not be useful to save, at the same time, 35% on water consumption and waste water output by using the grey-water reusing washing machine?

Anyway, much more water is desalinated daily, using other technologies, there are innumerable water desalinating plants (and organizations) throughout the world.

Unfortunately, there are no EU directives encouraging saving on water. But there is an EU directive stipulating that waste water output must be reduced by the member states gradually, each year. The introduction and spreading the of the grey-water reusing technologies will largely contribute to the success of that EU directive on waste water output. Apart from this improvement, on the final analysis, the biggest achievement of all will be the long lasting impetus that the progress of greywater reuse will give to the economies, during the long years, as it will become general, contributing to the sustainable development.

An earlier version of the invention can be seen in detail, with description on the following website:

www.geocities.com/paulokros/ .

There are four basic versions of the single tank greywater recycling system:

1. the tank alone, with mechanical operation, and eventually connected to the stronger than usual water pump of the washing machine;

2. fully electronic tank provided additionally with electronic control unit and pump and electronic water sensors and electro-magnetic water valves (enabling operation when greywater is not flowing into the tank with gravity free-fall).

3. the mechanical operated tank on top of a washing machine

4. the tank on top of a washing machine with fully electronic operation.

This diversification makes it possible that every region, according to its different development level could make use in some form of this new greywater reusing techniques. In less developed regions the mechanically operating tank can be used, which fits into the given level of the technological environment.

Useful links:

California gray water law (pdf)]


http://www.greywater.com/  ;


The Aquasave Project documented on CD

The European Commission, in the framework of the life-environment action (Life 97 Environment /IT/000106), financed 50% of total costs. This is excellent educational stuff and is worthwhile to download. After download, if necessary, it will want to install QuickTie 4, (your may have already a higher version) then you can choose English or Italian. The following 18 pages are copied from the CD. Enjoyable carefully chosen informative literature.

Definition of grey-water according to the California gray water law:

Graywater is untreated waste water which has not come into contact with toilet waste. Graywater includes waste water from bathtubs, showers, bathroom wash basins, clothes washing machines, and laundry tubs, or an equivalent discharge as approved by the Administrative Authority. It does not include waste water from kitchen sinks, photo lab sinks, dishwashers, or laundry water from soiled diapers.

The aim: I want to use the grey-water to flush the toilet, in order to save the fresh water quantity wasted on flushing the toilet.

The problem to be solved: Where and how to store a larger quantity of grey-water produced in our household? In an ordinary household, hundreds of litres of grey-water is produced daily by washing (washing machine, bath, shower).

The solution to the problem: one single tank which is capable to STORE, TREAT (filtering and disinfecting), and PORTION the greywater for toilet flushing, in full compliance with the greywater laws, while also assuming the traditional role of a toilet flushing tank.

The present infinitely simply system solves all these tasks with one‑single‑tank, where one‑and‑the‑same‑tank meets all these requirements, respecting all hygienic rules, in a closed system, with the required security measures.

A basic principle is to reuse grey‑water nearest in place and time, to where it was generated, i.e. within the confines of the household. The question: where to store so much water? I want to keep it as simple as possible.

Imagine a simple barrel of about 200 litres capacity. Similar sized boilers are in everyday use in many households. This barrel serves as a combined giant toilet flushing tank due to the very simple mechanism it holds. When you consider a simple toilet tank, with floater, just imagine that the height of the tank is increased to be ca. five times of its original height. But the floater is blocked at the original height with a limiter element. You can pour a lot more water into that higher tank. But how will it work? Simple! Fasten a long rod onto the floater, which goes through the water column above the floater and it rises over the water to reach the water valve above the water, in the top of the tank. When the floater goes down, just as in the ordinary toilet flushing tank, it opens the tapwater inlet valve to fill the tank. In our higher giant tank the floater works in the same way, with the help of the long actuating rod fixed onto the floater and also to the tapwater inlet valve in top of the tank. However, in practice this happens rarely, since much more grey-water is produced in a household than the water quantity which is needed to flush the toilet. In addition, rainwater can also arrive into the tank. Basically, only washing water is directed into the tank, it is enough for this purpose. So clean freshwater very rarely comes into the tank, only if the tank is completely emptied. The system is in continuous use, something is always happening, it is always working. There is almost always somebody in the family who uses either the toilet, or the bath or shower, or the washing machine, or it is raining, so (grey)water is coming and going all the time, so the greywater in the thank in moving and stirring constantly.

 Up to know the simplest grey-water reusing system was the "Twin‑flow", produced by the excellent German www.soltech.de company: Please, look at the picture in detail, and compare the different elements. The system on the picture is a perfect compact system, and merits acknowledgement and appreciation for its excellent solutions and engineering precision work. If you can appreciate this, you will understand the simplicity of the single‑tank system presented by the cartoon, as above.

Please, also watch the report on the AquaSave project, and compare its technical complicacy and its high costs involved in the project. Still, that project, too, merits our highest acknowledgements, because it is seeking a solution to the water shortage problem, and in addition, it is excellently documented, and the material is a perfect educational material on water management. I can only show all my respect and recognition to the excellent scientific and engineering experts who implemented that difficult experiment in Bologna, Italy.

What is grey water, and how a change in human consumption behaviour can improve the situation of water shortage

1.                           How much water do we have? 

Though more than two thirds of the Earth surface is covered by water, 97.5 percent of this is salt water. From the remaining 2.5%, 1% is forming ice in the North-Pole, and another percent is frozen in ice in the South-Pole. The remaining half percent can qualify as potable water, but about 90% of that half percent is stocked underground, which is not directly available. This means that less than one thousands of all the water is potable water on the surface of the Earth, but the distribution of that is not according to the population needs. Brazil, for instance, is rich in water, but where there is water, the population is scarce, and where the population is dense, water is scarce. In about 80% of the land, water is in short supply.

2.                           Global Water problems

a). Deforestation : by radically reducing the vegetation, the potable water is running off quickly to the rivers and seas and will become salt water. Deforestation contributes largely to the spreading of desert areas and to climate changes.

b). Spreading of desert : is partly the consequence of deforestation, i.e. inadequate human behaviour, partly the consequence of climate changes.

c). Climate changes: is a consequence of uncontrolled industrial expansion, causing extensive emission of gases like sulphur dioxide, carbon dioxide and other toxic gases, and a consequence of excessive deforestation.

d). Water pollution : Large ocean going vessels pour their sewage into the water without any treatment, and oil tanker accidents cause catastrophes endangering the habitat of many species of animals living in the ocean and in the seas. The largest part of the sewage produced by human population is flowing without any cleaning treatment into our rivers and sees, thus poisoning our waters.

e). Inappropriate consumption habits: People use too much water unwisely in their daily activities. The industrial development needs more and more water. Because of deforestation and climate changes, more and more water is needed for agricultural production. There is no agriculture without water.

f). Overpopulation : leads to deforestation, while more and more land is needed for production of more food. There is an exodus of rural population into the cities, an ever increasing number of people has been moving into the large agglomerations, contributing to excessive urbanisation, which, on the other hand is a major reason for water pollution.

Today, the population of our planet is around 6 billion, and 1/6th of them, about 1.2 billion people do not have potable water, which water is contaminated and is a major cause of mortality. On the other hand, according to the water usage statistics, only about 2% of domestic water consumption is used for drinking water, and not more than 15% is used for drinking and cooking. According to the statistical forecasts, between 2025 and 2030, the population of the Earth will reach eight billion, and half of them, around 4 billion will not have potable water of adequate quality. The above data shows that 85% of the water that we use in the household does not have to be of potable water quality.

3.                           It is insane to flush the toilet with potable water

In household water consumption ca. 35% is wasted on toilet flushing while the washing machine and bath/shower account for about 50% where the water becoming slightly polluted with soap/detergent is called "grey water" We can reuse that approximatively 50% grey water to flush the toilet. Water consumption statistical data varies very much, depending on geographical location and on socio-cultural factors. It is obvious that no potable water quality is needed to flush the toilet. The "water closet" was invented about 150 years ago in England, which is using water to flush the toilet. Since then, it has long become a so called "mod-con", i.e. it is taken for granted, and is considered as a modern convenience. However, it does not qualify as modern any more, since no major modification has been done to its functioning in the past one-and-a-half century. Therefore, the environmentalists have long attacked it as a water wasting equipment, and they suggest flushing the toilet with "grey water". In many areas where water is in short supply, there are serious restrictions in vigour on water usage. For instance, all of the states in the USA, and in Australia have their own "Grey Water Law" which strictly regulates what qualifies as grey water, and under what conditions it can be reused. There is also a special regulation, that no toilet tank having a capacity larger than 1.6 gallon (about 6 litres) can be put into commercial circulation, and the local government gives some contribution to the citizens who change their toilet tank to that smaller one.

4.                           Definition of grey water (US spelling: gray water)

The "California gray water law" is considered to be the strictest one of all the national grey water laws. It defines grey water as follows:

Graywater is untreated waste water which has not come into contact with toilet waste. Graywater includes waste water from bathtubs, showers, bathroom wash basins, clothes washing machines, and laundry tubs, or an equivalent discharge as approved by the Administrative Authority. It does not include waste water from kitchen sinks, photo lab sinks, dishwashers, or laundry water from soiled diapers.

It can be seen that grey does not mean the colour of the water, but rather it means the quality of the waste water. It is interesting to see that waste water from kitchen sinks does not qualify as grey water, it is already considered as "black water", because it may contain food remains and it is greasy. The most important criteria for reusing grey water are the following: Grey water can be reused only after filtering and disinfection. There are two types of grey water: 1. rainwater is considered a lighter grey water, because it does not contain so much contaminants, only leaves, feathers and other contaminants from birds. We can use rainwater to water the garden and food plants, and to wash the car. The darker grey water is washing water from the bath tub and from the washing machine, and that darker type needs more treatment, i.e. filtering and disinfecting, following which grey water can be used to flush the toilet.

5.                           The value of grey water

The value of grey water is equal to the price of the clean potable water it replaces.

6.                           Advantages of reusing grey water in the household:

1.                 by reusing grey water, we can save about 1/3 on household water consumption;

2.                 about one third on water and sewage bill;

3.                 it reduces waste water output by about 1/3;

4.                 last but not least, we can actively contribute to improving our environment.

Water availability : When we say that life on earth originated from water, we just mention a commonplace. However, it is not as banal to consider that water was the vital factor for the evolution of life on earth. Evolution lead the various living species, especially the human one, to select different types and amounts of water according to the needs to be faced.

The water of the oceans and of the seas turned out to be unfit for these needs. A further vital step in this evolution was the development of fresh waters.

The hydrologic cycle gives origin to meteoric water, that depending on the context it goes through results in fresh water.

Fresh water is a very small fraction of all water on the planet. Only 2,8 % (tantamount to 38.000.000 cubic kilometers) of all the water on the earth is fresh water. 2,5 % - 29.000.000 cubic kilometers - of this amount is frozen in polar ice and glaciers, while only the remaining 0,3% (9.000.000 cubic kilometers) can be used by all the living forms on the earth.

Fresh water - that is to say meteoric water made "fresh" by the context it goes through - can be roughly divided into two categories: 1) water from evapo-transpiration that infiltrates into the ground, is absorbed by the plants and is returned by the plants to the atmosphere and 2) run-off and infiltration water that are available for animal living forms in lakes, in watercourses and in groundwater tables.

Evapo-transpiration reintroduces into the atmosphere a percentage of water ranging from 56% and 82%. The remaining amount is partly run-off and partly infiltration water.

The actual availability of water also depends on the geomorphological context and the types of vegetation.

The hydrologic cycle distributes meteoric water unevenly. The amount of atmospheric precipitation depends on climatic factors (thermic excursions, atmospheric pressure, solar radiation etc.)

The most abundant atmospheric precipitations occur in South America (1648 millimeter per year), but only 35% runs off on the soil or infiltrates into the underground. In Europe, precipitation are lower than the half (734 millimeter per year), but as much as 43% runs off on the soil.


In Sicily in 1893, a four-days precipitation brought 1837 millimeters of rain. In Jamaica, in 1909, 3500 millimeter rain fell in eight days (3,5 meters). In a locality of India, in 1861, in one year 23 meters rain fell.


When Along with the annual amount and frequency of precipitation of a given area, it is important to know its pluviometric status, that is to say in what times of the year precipitation are concentrated. This may differ from region to region and may definitely affect the type of vegetation, the agriculture and the abundance of watercourses.

The flowing rate of a river in a given point of its course ranges during the year from peak values (high water) to minimal values (low water). Changes in the flowing rate may also occur in the space of the day, from season to season and from year to year.

These changes are related to the climate - for precipitation and evaporation - to the size of the catchment basin, to the geological status of the ground - for the permeability, that is to say the availability of the ground to be imbibed with water - to the thickness of the vegetational cover and to the altimetric status of the basin - slopes where water runs quickly or plain areas, where water stands longer, thus allowing infiltration, evaporation or use by man. Therefore, the flowing rate of a river results from a subtile dynamic balance, which is so significant in the description of the activity of a watercourse, that the change in the flowing rate in the space of one year defines the regimen of a river.

While a stream is marked by recurring high and low waters, the regimen of a river is more regular and active also during the dry seasons.


Surface water

The surface water originating from rain and snow first flows on the soil like a great veil, then it divides into streams that flow into watercourses with an increasingly high water flow.

The water flow of a stream is the amount of water, expressed in cubic metres that goes through its section every second.

For e.g., the water flow of the Nile - one of the longest rivers in the world (6671 kilometres) - is 2000 cubic metres per second, while, surprisingly, the water flow of the Amazon - slightly shorter than the Nile (6280 kilometres) - is 100,000 cubic metres per second.

These remarkable differences in the water flow of rivers result from the rainfall in the geographic area of the river and from the surface area of the hydrographic basin, that is to say the area from where all water supplied to the river (rainwater or water from the sources) is collected.

Lakes are masses of water with different origins, extensions and depths and are among the sources of water supply for the hydrographic basins. One or more watercourses, called tributaries, enter the lakes, while other watercourses, called outlets, transport the outgoing water. If there are no tributaries, the lake is supplied only by rainwater or by subsurface water.

If there are no outlets, water is lost as a result of evaporation or goes out through the underground circulation.

Lakes have a glacial origin, if they occupy depressions at high altitudes produced by the action of glaciers in the past. Other lakes fill depressions formed by movement of the earth surface along geological fractures called faults. Volcanic lakes are contained in craters of extinct volcanoes. Damming lakes were formed by the accumulation of material brought about by landslides.

Artificial lakes are special water bodies: their aim is to stem floods, supply water for the hydro-electric energy, store water for uses such as the supply of drinking water and the irrigation of crops that require water (rice, maize, vegetables etc.)

Every watercourse is a component of a larger system based on a complex balance. An action on a water body - for example the costruction of a dam - or on one part of it may have repercussions on a wide-reaching area and at a far distance.

Artificial lakes, like natural lakes, receive sediments. For e.g. it has been estimated that by the year 2025 the half of the capacity of the Nasser lake - dammed by the great Assuan dike - will have been filled by sediments. The Nasser lake has a surface area of 500 square kilometres and collects two billion cubic metres of water. Thus, it determines the evaporation, the water supply of aquifers and the water flow of the river. Moreover, it influences the productivity of the soil - that does not receive the fertile slime any more – the extension of marsh areas, the industrial production, the fishing and the erosion of the river delta. An accurate preliminary analysis could have helped to control the problems resulting from the action of the lake.


Ground water

Subsurface waters are the most important reservoir of fresh water on the earth. The volume of underground water - according to the estimate of UNESCO - is forty times higher that the one of surface water bodies, that is to say mainly lakes and rivers.

Subsurface waters mainly occur in geologic bodies called "aquifers". They are made up of permeable rocks, that is to say rocks where water can infiltrate, when it has a certain load. Permeability can result from porosity or from cracking.

Porosity is typical for loose rocks, such as gravel and sand, that make up the main aluvial aquifers - originating from material transported by watercourses - and that show communicating voids among the grains. Cracking is typical for rocks with splits and great or small discontinuities. The circulation of water through the void areas occurs in the saturation zone (line) as a result of gravity.

This area is separated from the overlying aeration zone - where water only occurs as a thin layer on rocks grains - by a piezometric layer. Precipitation water and water from the surface water of bodies infiltrates into the soil through the aeration zone and then it reaches the saturation zone. The amount of infiltrated water depends on the permeability of the aquifer rocks and also on the following factors:

1. amount of precipitation

2. balance between the evaporation from the soil and the infiltration into the underground

3. absorption of vegetation

4. amount of water returned to the surface of water bodies through the sources

5. underground water extracted by man

Subsurface water can be extracted from aquifers by wells and sources.

Therefore, this is the most important source of water supply for the human activities (agriculture, industry, civil and domestic use).

Underground water can move inside the aquifer at speeds ranging from some centimetres to several metres a day. This allows to restore the water supply after the extraction.

However, if the extraction rate is too fast compared to the rate of supply to the aquifer, the aquifer gets progressively drained. The constant sinking of the piezometric surface results in the depression of the aquifer. In some cases, the effect is a sinking of the soil called subsidence.


A glacier is a large mass of ice that is formed on the mainland as a result of the tamping and crystalisation of steadily moving snow. As snow is the primary factor for the formation of the ice mass, glaciers develop only in areas where the snowfall in the winter is higher than the snow melting in the summer. The boundary of persistant snow, that is to say the inferior limit of the glacier, varies remarkably. In cold polar areas, the limit may correspond to the sea level, while in intertropical regions, this boundary can only exist in high mountains, frequently over 4500 metres.


Water falling as snow at high altitudes or latitudes cannot infiltrate into the ground or run off immediately. It remains for a more or less long time in the form of ice. Sooner or later, the ice gradually melts and the water can flow to the sea. In the meanwhile, it can remain captured in the glacier for tens, hundreds or also thousand of years. Research studies about the glacial cover of Greenland indicate that one part of that ice is more than 25000 years old.

How much water is frozen as ice? According to some estimates, only 2,5% of the total water reserves of our planet occurs in the form of glaciers. However, this is a misleading figure, as the amount of ice water in absolute terms is 29 million cubic kilometres.

In mountain areas, there are thousands of relatively small glaciers. They usually occur in mountain valleys and are called alpine glaciers. The total amount of alpine glaciers is about 210.000 cubic kilometres, which almost equals the total volume of the lakes on the earth.

On a larger scale, continental glaciers are huge ice accumulations that do not only occupy valleys, as in the case of alpine glaciers, but cover much more extended areas.

Presently, two great continental glaciers occur on the earth. One covers the whole area of Greenland, the other one covers the entire antarctic area and constitutes about 10% of the earth surface.

If all continental ice should melt, the sea level would increase by 60-70 metres and would flood many densely populated coast areas. To have a clearer idea of the amount of continental ice, if the antarctic ice should melt, it supply water to a river such as the Mississipi for more than 50.000 years or to the Amazon for about 5000 years or to all rivers of the world for 750 years.

Water pollution

The pollution of natural water, as in the case of any other environmental resource, is an alteration that can have harmful effects on the living organisms. Water pollution occurs through the introduction of foreign substances whose features alter the natural quality of water, thereby preventing it from being used and making unpleasant for the sight, the taste and the smell.

The pollution of surface and ground water is a factor that limits some or all uses of water for man. Drinking is the most vulnerable sector of use. Pollution frequently prevents a

source of natural water from being used for drinking , thus also limiting the use for less demanding sectors such as the agricultural and the industrial one. Incredibly, a small fraction of pollutant can make huge amounts of water non drinkable. For e.g. a tea-spoon of tetrachloriethylene can dangerously contaminante one million litres water.

The pollution of underground water is usually more difficult to be detected than surface water pollution. In many cases, underground water pollution is reported only as a result of controls of the health authority. The resulting measure is usually the interruption of the water supply in the municipal system. In this case, the source of pollution is very difficult to identify, as it may be very far from the point, where pollution was detected. Moreover, the action of the polluting agent may have ceased long before the detection and pollution may also result from a combination of factors in the area where water is supplied to the aquifer.

The signs of pollution of surface water are the devastating effects along a watercourse, on the banks or on the surface of a lake such as oil stains, dead fish, foams, coloured water and unpleasant or unusual smell.

Surface water may also be affected by the pollution resulting from the washing off of nitrates from the agricultural soil or of anti-freeze products from the highways, caused by precipitation.


Interview to Kay Barlund

Extract of an interview withMr. Barlund, United Nations Economic Commission for Europe  Mr. Kaj B.rlund is the Director of the Environment and Human Settlements Division of the United Nations Economic Commission for Europe (UN-ECE).

He is a former minister of the environment of Finland.

- Is fresh water a problem in European cities?

Kaj B.rlund: Yes, and it’s a problem that won’t go away! There is a real danger that water shortage might actually restrict the growth of cities.  What are the reasons behind this phenomenon? Increasing urbanization, decreasing water-supply, due in particular to the depletion of groundwater resources, and the waste of water in general are among the most obvious reasons. Yet an even greater threat is the obsolescence of the water-supply system.

- Isn’t this system regularly maintained?

No, not even in the most developed countries, let alone in the countries in transition to a market economy. In most countries of the UN-ECE region the system of pipes to supply water is in a desperate state. In many cases the pipe systems date from before World War I and they haven’t been upgraded since.

- How big is the leakage?

On average between 40 and 60% of the water which is produced is lost before arriving at the tap. But in some cities the lost water amounts to 80% of production. To give you a concrete example, in Norway, which can be considered as a model in terms of environmental protection, the figures are clearly stunning. 3.9 million people are connected to the water distribution system. On average the total amount of water delivered by the waterworks nationwide is some 600 litres per day per person. But average consumption has been estimated at only 320 litres per day per person. This means that around 45% of the production is lost in the distribution network.

- Where do these losses occur?

Mostly in the municipal supply system. In fact, sometimes the "best" thing that can happen is for a pipe to burst, because then the authorities are obliged to repair it. But mostly the leaks are "small" and can go undetected for many years. And even then there is no guarantee that they will be repaired.

- What happens with this lost water?

It infiltrates the ground. Either it remains there creating large humid zones or in very many cases it infiltrates the sewerage system. In this case it implies an enormous economic cost to the communities. First, this water never reaches the tap; second, it increases the amount of water to be treated in waste-water plants; and, third, in some cases the treatment capacity has to be 50% higher than it should have been if there had been no leaks.

- How much does this all cost?

We have tried to estimate the economic cost of these leakages for the whole of the ECE region, and our conservative estimate is around US$ 10 billion a year in terms of clean water wasted alone. But that is only one aspect of the economic costs of leaks. One has also to take into account the damage that these leaks do to the foundations of houses and other constructions. And this aspect is very difficult to estimate.

- Do they affect human health?

Yes, definitely. What happens is that these leakages create large reservoirs of water full of bacteria. As long as the pressure is constant these bacteria should not infiltrate the pipe system. But as soon as the water pressure drops they are pumped into the pipe and directly into the taps. Their presence is not detected because such tests are carried out before the water leaves the pumping station, not afterwards.

- Has it been noticed?

Yes, in many UN-ECE countries there has been a very clear increase in Escherichia coli in the water-supply.

- So why are these leaks not repaired?

For a number of reasons. First of all, these repairs are costly and mainly to be paid by the municipalities, which in most countries of the region are facing serious financial difficulties. Furthermore, the effects of these repairs are not "visible". In fact, as long as the leaks remain small, the public at large is not aware that water is being wasted. And let’s face it, even many householders ignore small leaks for a long period of time because it costs less to waste the water than to call a plumber.

Another factor has appeared in several countries in the region, namely the privatization of the water-supply companies. In many cases these companies, which have fixed-term leases, have very little incentive to undertake any large-scale long-term investment in restoring the pipe system. I suppose that as long as they have no precise obligations to do so, very few of them are going to make these investments.

- What is the scale of the problem?

In many cities of the UN-ECE region the entire water system would need to be rebuilt. But these are huge infrastructure works and would imply that most of the streets of these cities would have to be opened up. You also have to realize that the problem lies not only with the big cities themselves. The economic development of the surrounding areas is also compromised, because as cities take more water than they actually need, they are in effect taking it from their surrounding areas.

- What can be done?

Unfortunately, these issues have not attracted much political interest. Only major disasters

seem to do that. In the UN-ECE we have been working on water issues since the late 1960s, but the problem has now taken on such proportions that we feel we have to raise awareness about this crucial subject. The most important thing is to include provisions for the renewal of individual and collective water- supply systems in renovation programmes for cities and to oblige water-supply companies to monitor and maintain their water-supply systems.

It is up to Governments to launch awareness campaigns for the public at large but also for municipalities and companies to remind them that water can no longer be considered as a free gift of nature and that there is a need to change the approach to water use. These campaigns could be supplemented by a number of economic incentives like metering water use and a more realistic pricing of water, which should take into account the investment needs for the renewal of the pipe infrastructure. Otherwise, many major cities in the ECE region may very well end up having to accept a reduction in the quantity and quality of the water that is supplied to them.


Remarks about the ancient water supply system of the Royal College of Spain in Bologna

It was the year 1364 when Cardinal Egidio Albornoz established in his testament that a part of his goods should have been used for the construction, in a suited area of the city of Bologna, of a "Casa Spagnola" - a Spanish House - that is to say a complex of buildings designed to house the Spanish students of the University of Bologna. After choosing and purchasing the ground, the design of the new complex was commissioned to Matteo Gattapone da Gubbio, who was the personal "ingegnerius, geumetra and mensurator" of the Cardinal Albornoz. Works started in May 1365 and were finished in the space of one year, so that already in 1368 the first students could establish in the college. At that time the city of Bologna did not have an aqueduct, as the excellent aqueduct built in the 1st century b.C. - probably under the rule of Augustus - had fallen into disuse for centuries. In the great new college the water supply could only be achieved by wells and reservoirs. As the area of the college - that is adjacent to the southern side of the second-last circle of walls of the city, built between the 12th and the 13th century, the socalled walls of the Thousand - had long been occupied by houses and handicraft workshops, also with vegetable gardens and vineyards, there were probably many wells present already.

Possibly, a certain number of them were preserved and became the first water-supply sources for the new "Spanish House". One well preserved for use seems to be the one still to be seen in the southern corner of the great two-tier courtyard - the heart of the entire complex. The diameter seems to be typical of the metric system used in the Roman age, thus suggesting that at the time of the establishment of the college the well was already thousand years old.

As the well occupied the corner of the courtyard, the rest of the courtyard was available for a great tank, where rainwater from the roofs of the surrounding buildings could be collected.The reservoir was constructed in 1578 by Giovanni Battista Tibaldi, the entrepreneur in charge with the masonry works of the college. An underground vaulted chamber was built with enough capacity to contain a considerable reserve of good-quality water for the college. Among the other things, the water from the reservoir was more suited for kitchen uses than the water from the wells.

By a lucky chance - but also probably thanks to the care in the maintenance of the structure by all those who ruled and were in charge of the college - the underground tank with its Verona marble upper opening and its two access doors from above was preserved What is more, three of the four pipings for collecting rainwater from the corners of the courtyard are still preserved, equipped with the original sedimentation systems. As far as we know, this is the only surviving example in Bologna.

This is a sort of by-pass system, where the occasional rainwater not suited for preservation was carried to the sewage and the persistant autumn and winter rain was conveyed to the tank. This preciously useful water went through a sedimentation process before the access to the pipes leading to the tank. The sedimentation occured with a sandstone ring jutting from the floor around the mouth of the pipe. The water overflowed from the rim of the ring after the sedimentation from the residual powders and corpuscles that were left over despite the regular washing of the collecting surfaces - the roofs and the floor of the courtyard - The system of defence from the foreign bodies was completed with a "grasparola", a sort of copper net placed on the hole of the sewage discharge or at the mouth of the pipe conveying to the tank.


The WaterCare media campaign aims to raise awareness of water issues throughout South Australia.

WaterCare focuses on three key themes: sustainability, efficiency and stormwater pollution. These themes have been identified through market research as the most important for South Australia to address.

By focusing on the three themes WaterCare will encourage positive behaviours toward water conservation and improving water quality.

The WaterCare advertising campaign is designed to

                                 remind all South Australians that our water resources are precious

                                 increase awareness that our water issues are long term

                                 increase understanding that our behaviour impacts on our water resources

                                 encourage the community to protect our precious water resources

The campaign predominantly focuses on television and print advertising. The television campaign is designed to raise the emotional awareness of water as a precious resource. While, the print component provides more detail on the water issues we face as a State.

To view the WaterCare television campaign please click below.



Improving systems


- Selection of crops with a high yield for each litre of transpired water

- Use of systems of crop combinations for a maximized exploitation of the humidity of the ground

- Selection of crops based on the climatic conditions and on the actual availability of water

- Alternate crops to maximize the production when water and soil have a high salinity rate

- Selection of dryness-resistant crops in case of water shortage - Sowing crops with an efficient water yield Management:

- Improvement of the time planning of irrigation

- Improvement of the use of canals for measured supplies

- Supply of water in the best suited times for the growth of crops

- Development of ploughing and soil preparation systems designed for the conservation of water

- Better maintenance of canals and of the related devices.

- Recycling of drainage water

- Creation of organisations of water consumers aimed at a larger involment of farmers and at achieving a more efficient tariff system

- Reducing subsidies for irrigation and/or establishing tariffs that favour water saving

- Establishing norms aimed at creating a more equitable and efficient market.

- Adjusting the rural facilities to favour the use of more efficient technologies in the private sector

- Improvement and promotion of training


- Leveling of the ground for a more uniform distribution of water

- Spray irrigation to improve the distribution of water

- Efficient sprayers for a more uniform distribution of water

- Sprayers with low-energy precision devices to reduce losses caused by wind and


- Argins along the furrows to favour infiltration into the soil and to reduce the amount of water running on the surface

- Dripping irrigation to reduce evaporation and the other factors of water loss and to increase the crop yield (Source: Amy L. Vickers, Handbook of Water Use and Conservation)

Goals of the Aquasave project

to develop behaviours and technologies meeting the water needs in urban areas with consumption habits that are compatible with the protection of the environment in the framework of a saveguard strategy of the water resource to implement an integrated system for the saving, the recycling and the re-use of water in eight newly built flats. The system is based on the assumption that out of the 250 daily litres of drinking water used every inhabitant only 4% must be high-quality water. The remaining part is designed for less "precious" uses or it is wasted as a result of the carelessness of the users or of badly devised sanitary facilities. to examine the reliability of the system, the possibility of using the system in very different sectors from the one designed for the experiment, the enviromental and economic benefits of the system and to verify the unchanged comfort for the user despite the reduced consumption.


World experiences


The "Anglian Water" is a British body for the water supply to five million inhabitants living the eastern area of England.

In the middle of the Eighties, the "Anglian Water" launched a long monitoring campaign of water use. The program was carried out on 2000 flats, of which 100 were equipped with water-metres for measuring warm and cold water, the water discharged and the water used by the each tap system such as: bath-tubs, showers, washing-machines, bidets etc.

The result was that the use of grey water was 42% of the total consumption of water, which was much higher the water needed for the supply of water closet flush tanks, about 34% of total water consumption. In terms of quality, the values of PH, COD, BOD5, total coliforms and Eschirichia Coli were measured. The results are published in the table.


In this case, the use of non conventional water was designed both for irrigation - due to a high content of salt, groundwater in this area is not suitable for long-term irrigation - and for compensating the exhaustion of some wells resulting from a considerable population growth. In the case in point, all water from the roofs is used and treated with the following procedures: sedimentation inside a stocking reservoir; preliminary disinfection through UV rays; sand-filtering; second filtering on a 20 millimetre cartridge; storage in a reservoir.

Presently, the stocked water is used only for irrigation, but the system can also produce water for domestic uses.


The adoption of the program resulted from the need of improving the living standard of inhabitants of very arid areas, where the shortage of water makes the growth and the maintenance of gardens very difficult and costly.

Therefore, grey water and rainwater are stored for irrigation uses. All the water is filtered through a sand filter and then conveyed to a reservoir that supplies an underground irrigation system, specially equipped with biocompatible pipings.

In order to minimise losses, the house is also equipped with low-flow supply apparatus and water closet flush tanks.

With these equipments a water-saving of 570 cubic metres a year was achieved. Also in this case the disadvantages were basically related to the costs of the treatment plants.



The reuse of grey water was also designed for the conservation of nutrients, especially of phosporus. Unlike carbon and nitrogen, phosphorus does not have a gaseous form. It is to be found in the water as a result of the dissolution of phosphatic rocks and it is lost as a result of the discharge of sediments into the sea or in the purifying muds. To counterbalance this loss, the idea was developed to separate water types with different compositions, especially for the content of phosphorus, coming from the different service sectors in houses (see table).

In the case of Gavle, this approach led to the development of systems of differentiated storage for urines, faeces and grey water according to the following indications:

- urines, that contain 80% of the nutrients, are easily stored and stocked for agricultural uses

- faeces are stored, composted for six months for the elimination of pathogenic agents and recycled for agricultural uses

- grey water is purified with a natural biological process and then designed for the typical uses for grey water or as a replacement for drinking water.


This is an experimental project implemented in 1985 where grey water and rainwater are reused and where water closet flush tanks with a capacity of six litre and tap systems (taps, showers) with a low-flow aeration are used.

Grey water - reused in flush tanks, designed for irrigation and partly stocked during the winter for the summer needs - is treated by processes of sedimentation (inside the stocking reservoir), filtering and disinfection.

Rainwater from the roof is used only for irrigation and designed for uses not related to the household. It goes only through one phase of filtering by means of a metallic filter.

Thanks to these systems, the water consumption was reduced by over 55%. Interestingly, these types of flush tanks allow a decreased consumption from the usual average of 115 litre per inhabitant to 34 litres.

The disadvantages of this solution are obviously economic, as the charges for the application are to be borne by the house-owner.


The goal of the installation in Austin - dating back to 1987 - was to maximize the exploitation of rainwater in a desert area.

Two systems of water collection were designed. The first one was implemented on the house roof: water is stocked in special tanks and used only for irrigation. The second one was installed on the roof of a barn with an area of 18 square metres and made of galvanised steel: rainwater is collected, stored and treated with the aim of making it drinkable. Water is pumped to two filters with cartridges in sequence with a porosity of 5 and 1 micron and then disinfected with UV-rays. The standards achieved with this water treatment comply with the limits stated by the local legislation. The water supply to the users in this house almost equals the average recorded in Texas which is about 227 litres per inhabitant - which is much lower than the total average in the United States.


The first examined case is a residential allotment in Osborne, in the south of Australia, called New Haven Village, made up of 65 one-family houses. The building was designed to minimise the impact on the environment, as it is equipped with plants for energy-saving and for the re-use of grey water and rainwater.

This settlement was build for demostration purposes. Its goals were:

- researching a system of working for treatment plants that is more economical than the present one, where centralized plants are used

- experimenting a system of water resources that can be reproduced in areas with similar conditions

- minimize waste water from the sewage

- minimize the use of drinking water for external uses

The New Haven Village is equipped with a small treatment plant placed in one area of the buildings where rainwater and grey water are treated. The out-going fluid is used for irrigation and for the supply of the water closet flush tanks. In the treatment system, the first rainwater is conveyed to a grinding pump and then conveyed to an aeration tank together with grey water. Water is sand-filtered and then disinfected with UV-rays.


The system implemented in 1996 in Canada has been designed for recycling rainwater for drinking uses and for re-circulating both grey water and blackwater for the supply of flush tanks and for the irrigation of gardens.

After having been collected and stored, rainwater goes through two filtering phases – one working with sand and the other with active carbon - and then it is disinfected with UV rays. This system, combined with the high rate of rainfall, can entirely replace the use of drinking water.

Grey and black water are stored in a reservoir where the separation of oils and fats is performed and then conveyed to another aerated biological filter, where the removal of organic matter and the nitrification of nitrogen is carried out. Water is then conveyed to a slow sand filter, then to a carbon filter, disinfected with UV rays and stocked.

The advantage of these systems lies in the total re-use "in situ" of all water, while the disadvantages are related to the very expensive maintenance for the user.


Dissemination and divulgation

a) In the monthly magazine "Pratica" published by the Editariale Italiana, an issue of the special insert "Speciale Casa"- with an average total circulation of 40.000 copies – was dedicated to the Project Aquasave.

b) Two interviews were broadcasted. One interview was given during the program "Viaggio in Italia" on the national broadcasting station Radio Rai Uno. The other one took place on the station Rai International during one issue of the program "Un’ora con voi" dedicated to desertification.

c) On the occasion of the opening ceremony of the flats, press releases were made on local and national newspapers. Programs were made on the some TV local stations and on the regional news of the national station RAI 3.

d) Participation to the one-day convention dedicated to water reclaim and saving in the urban ecosystem which took place in Bologna on October 23rd 1998. A strong emphasis was placed on the Project Aquasave. 200 copies of the records of the convention were distributed during the National Conference on Energy and Environment on November 25th-28th 1998.

e) A written report was presented during the convention "Water security in the third millenium" organized by the Landau Network in Como.

f) A paper on the Aquasave project was presented during the international convention in Lausanne "Emerging Technologies for Land Use and Water Management"

g) A paper on the Aquasave project was presented during the international symposium in Davis (California).

h) Presentation of the project at the fair of the reclaim and recycling of material and energy that took place in Rimini on November 8th-11th 2000 in the seminars and posters session.

COMPONENTS (Commercial technologies for water-saving)

  One-gauge water taps with controlled flowing and equipped with jet-breaking devices - the so-called Venturi effect where the introduction of air into the water causes an increased volume of the water flow and thus a reduced water consumption with an unchanged washing efficiency

  Water closet flush tank equipped with a double flushing system. It is a "twobutton"

system where the small tank discharges 3,5 litres, the larger one discharges 6 litres.

 Toilet bowl equipped with a hydrodynamic system for optimising the flushing

 Automatic flushing system in the WC with a sensor detecting the approaching user and automatically triggering a slight flushing. Remark: it is installed only in one floor.

 Showers with an electronic system for regulating the flow and the temperature of water

 Washing-machines and dish-washers of the last generation with a low water consumption, equipped with a double supply system for drinking water and for rainwater.


Plant engineering

GREY WATER - Grey water from the washing of hands, from showers and from baths is collected by means of a specially designed system and conveyed to a reservoir in the machinery room.

Then, it is treated, stored and conveyed through an autoclave to the flats and then to the water closet flush tanks.

Treatement of grey water - The system of treatment of grey water consists of:

a) pre-treatment (grilling: 0.5 millimetres: pre-disinfection)

b) storage of the incoming water

c) sand filtering (about 50 micron)

d) microstraining with polyethylene membranes

e) disinfection with peracetic acid (about 4 ppm)

f) stocking of the treated grey water

g) pumping by autoclave for the supply of the single tap systems

The volumes of the tanks are the following ones:

Volume of the tank for the storage of grey water: 4 cubic metres. The capacity is designed for the simultaneous storage of grey water from all bathrooms.

Volume of the stocking tank for the accumulation of treated grey water: about 5 cubic metres

Volume of the autoclave for the supply of water into the water closet flush tanks: about 0.3 cubic metres.

RAIN WATER - Rainwater from the roof is stored by means of a specially designed system and conveyed to a storage tank in the machinery room. It is treated and carried to two stocking reservoirs to create a reserve for times of scarce rainfall. It is conveyed by an autoclave to the flats and then to the washing machines and the dish washers.

Treatment of rainwater - The system of treatment of rainwater consists of

a) drainage deviation of the first rainwater

b) pre-treatment (grilling: 0.5 millimetres: pre-disinfection)

c) storage of the incoming water

d) sand filtering (about 50 micron)

e) microstraining with polyethylene membranes

f) disinfection with peracetic acid (4 ppm)

g) stocking of the treated grey water

h) pumping by autoclave for the supply of the single tap systems

Features of the plant - Volume of the reservoir for the storage of rainwater: around 10 cubic metres

Stocking reservoirs: 20 m. In case of prolonged shortage of rainfall and of exhaustion of water from reserves, drinking water is supplied.

Volume of the autoclave for the supply of washing machines and dish-washers: about 0.3 cubic metres.

Yearly rainfall: 600-680 millimetres of water

Area of the roof: about 200 cubic metres

Rainwater that can be used for washing: 100 cubic metres

A combination of rainwater and drinking water from the municipal water supply system is used for the household appliances. Rainwater is used for pre-washing, washing and rinsing with the exception of the last rinse. Washing machines and dish-washers are designed to automatically draw rainwater first and then drinking water.


Control and monitoring

All experimental households are equipped with technological instruments that can inform the user about water use and water costs in real time.

An integrated monitoring system with the following components has been installed:

(a) instruments for measuring water consumption on the single tap systems - taps, shower etc

(b) instruments that can perform on-line analysis of some quality standards - such as probes on the roof measuring the conductivity and the turbidity of rainwater

(c) stations for sampling treated and untreated water in the framework of a monitoring campaign of the chemico-physical and microbiological features of water

(d) electronic panels for real-time information to each user about the trend of consumption and the estimated costs.


Set of rules

AUSTRALIA: REGULATION: Draft Guidelinese for sewarege system- Use of Reclaimed Water, ISSUING BOARD: National Health and Medical Research Council, YEAR: 1996, RANGE OF USE: Irrigation, water closet flush tanks, vehicles washing, pH: 6,5-8  TURBIDITY: < 2 NTU



REGULATION: New South Wales Guidelines for urban and residential use of reclaimed water

ISSUING BOARD: NSW Recycled water coordination committe

YEAR: 1993

RANGE OF USE: Urban uses outside the houses

COLOUR: < 15 TCU, pH:6,5-8  TURBIDITY: < 2 NTU


COLIFORMI TOTALI: <2,5/100 ml - The values refer to the point of use

GERMANY: REGULATION: Requirements of DIN 1988 in respect of rainwater utilization facilities, YEAR: 1988 - Only technical prescriptions

JAPAN:  REGULATION: Draft Technical Guidelines for Wastewater Reclamation and reuse, ISSUING BOARD: Ministry of Construction

YEAR: 1981 - RANGE OF USE: Water closet flush tanks,

APPEARANCE: Not unpleasant

SMELL: Not unpleasant

pH: 5,8-8,6


TOTAL COLIFORMS: < 10 count/ml

UNITED KINGDOM - REGULATION: Implications of using recycled greywater and stored rainwater in the UK


RANGE OF USE: Water closet flush tanks, cloth washing, irrigation, fire extinction


Suggested regulations

ITALY, REGULATION: Testo aggiornato del decreto legislativo 11 maggio 1999, n. 152, recante: "Disposizioni, sulla tutela delle acque dall’inquinamento e recepimento della direttiva 91/271/CEE", YEAR: S.O. G. U. n. 24 del 20.10.2000, REFERENCES, Art. 1 - punto 2-f, Art. 26

UNITED STATES - REGULATION: EPA/625/R-92/004 “Guidelinese for water reuse, ISSUING BOARD:EPA, YEAR: 1992


Irrigation, water closet flush tanks, fire extinction, air-conditioners

pH: 6-9


BOD:<10 mg/l



* in California 2,2 coli in 100 millilitres

REGULATION: Proposed Revisions to reuse of Reclaimed Water and Land Applications, ISSUING BOARD:

Florida Department of Environmental protection -  YEAR: 1995

RANGE OF USE: Irrigation, water closet flush tanks, fire extinction, fountains


BOD: <20 mg/l


REGULATION: - NSF 41-1983 Wastewater recycle/reuse and water conservation devices, ISSUING BOARD: NSF International Standard

YEAR: 1983, RANGE OF USE:Use involving possible contact with man

APPEARANCE:Absence of oils and foams

SMELL: Not unpleasant



BOD: < 45 mg/l average for seven days

TOTAL COLIFORMS: <240/100 ml


download of the cd-rom version* in English

* You can download the fully version of the cd-rom. 

Pay attention! The download may be very long (over half an hour) because the file is long as 350Mb. The file is in .zip format. After the dowload you may unzip it and click on "start" The cd-rom version is like others cd-rom with interactive opportunities and movies. There are possible sound problems.


GrayWater Literature - TEXAS, USA (pdf, 141 pages)


Farmhand Foundation Publications – Australia  

Truth in Water Entitlements (Complete)  (PDF 766KB)

Talking Water - Comprehensive 12 Part Report (Total size approx. 4MB)
Part 1, Introduction - PDF 766KB

Part 2, The Future - PDF 295KB
Part 3, What you can do - PDF 104KB
Part 4, Ideas for our water - PDF 26KB
Part 5, More efficient - PDF 607KB
Part 6, Recycling our water - PDF 237KB
Part 7, Storing more water - PDF 199KB
Part 8, Producing more water - PDF 205KB
Part 9, Transporting water - PDF 269KB
Part 10, Engineering the weather - PDF 405KB
Part 11, Australia's water - PDF 611KB
Part 12, Acknowledgements - PDF 188KB

Water Strategy Launch   (PDF 185KB)

Five Point Plan   (PDF 173KB)

Drought Facts   (PDF 508KB)

Ways to Save Water   (PDF 162KB)

SeaWater Desalination

GE proudly boasts that 7 billion litres of water is desalinated daily using GE Water Technology. We must acknowledge, this is really a big achievement. This also shows how big the water shortage problem is. Still, would it not be useful to save, at the same time, 35% on water consumption and waste water output by using the grey-water reusing washing machine?

Dubai produce something like 70-80% of its drinking water through desalination.  One of the things I'll be checking out when I'm there is the quality and taste of desalinated drinking water.  Reverse osmosis seems to produce a good, crisp feel to drinking water, and the article below indicates it's become a prime part of desalination.

Desalinated water a sweet deal, a sticky problem

MEXICO CITY, March 20, 2006 (AFP) - Desalinating sea water for coastal populations is 10 times cheaper than in the 1990s, experts note, while others warn of environmental hazards.

"A dozen years ago, desalination cost eight dollars per cubic meter," said Loic Chauvin, president of the France-based World Water Council.

"Now, we are at 80 cents, one tenth as much, and that is sure to fall," he said.

Gerard Payen, environment advisor to UN Secretary General Kofi Annan, agreed.

"Desalination is well along, works very well.

"However, it takes sea water and energy," he said. "Because the cost of desalination depends on the cost of energy," he said, "the technology is most highly developed in countries with sources of energy or which are on islands, where there is no other choice."

Desalination plants have adapted to the needs of dry and desert regions, to produce water for drinking, irrigation or industrial use.

Countries around the Gulf are the prime consumers. Two thirds of the world's desalination capacity is installed on the Arabian Peninsula.

Beyond the Gulf and the Caribbean, the United States, Spain and Israel use the technology.

Desalination is common at seaside luxury hotels, such as in Baja California or the Dead Sea, which have an additional source of clean water.
GE estimates that 2.6 billion dollars are spent on desalination. The company is building
Africa's largest sea water desalination plant, in Algeria.

The Hamma plant outside Algiers will meet the water needs of 25 percent of the capital's population when it goes on line in 2007, and is cost-effective, according to GE head of marketing for the Americas, Gabriela Cabrera.

"It is not as expensive as many people think, the benefits are greater than the investment and it is a sustainable source of water," she said.

Environmental groups do not agree. They say the leftover salt jeopardizes marine flora and fauna and that desalination uses a lot of fossil fuel.


Factsheet (2.3 Wastewater Reuse, PDF)  Onsite wastewater reuse provides numerous opportunities to reduce water use within the home…

Create an Oasis with Greywater, Excerpt ~ The Gravity Drum

Greywater Treatment and Reuse, Tufileh, Jordan. (Cities Feeding People)  Using a revolving fund, the CARE-financed permaculture pilot and greywater reuse project (PPP) in Tufileh, Jordan, helped about 50 poor periurban families recover household greywater to grow fruit and vegetables. An IDRC-funded evaluation of the project indicated that it helped families preserve valuable freshwater, achieve greater food security and generate income through sales of produce…

Greywater Treatment and Reuse for Peri-Urban Horticulture - (West Bank, Palestine)  The main objective is the standardization of means and methods for the up-scaling and replication of onsite greywater treatment plants for decentralized aggregates of 15 to 20 houses  

Greywater Treatment and Reuse in West Bekaa, Lebanon  Initially, it involves the implementation of greywater treatment systems using trickle filters in 30 homes. The results will then be extended throughout a five-community cluster of surrounding villages….…

Safe Use of Household Greywater, Guide M-106. Revised by Marsha Duttle, Extension Research Assistant -College of Agriculture & Home Economics- New Mexico State University

The New Mexico Environment Department and the Construction Industries Division govern liquid waste disposal in New Mexico, and issue permits for approved systems. Greywater use is restricted by the Liquid Waste Disposal Regulations (LWDR), but the Environment Department can grant a variance

if the applicant shows that:…

Sustainable Options for Domestic Water Sewage, by: Bob Patrick. (Part of a group project, Geography 449 class Spring 1999 Semester - Directed by Dr. Mark Roseland Ph.D. MCIP)  Investigate potential for greywater treatment and reuse for irrigation/fireflow purposes…

Greywater Reuse: Some Options For Western Australia, by: Martin Anda, Dr. Goen Ho, Dr. Kuruvilla Mathew

Five Options Currently Under Research For Western Australia

Small Scale Water Recycling Systems - Risk Assessment and Modelling, by: C. Diaper, A. Dixon, D. Butler, A. Fewkes, S.A. Parsons, M. Strathern, T. Stephenson and J. Strutt. Water Science & Technology Vol 43 No 10 pp 83–90 © IWA Publishing 2001    This paper aims to use quantitative risk analysis, risk modelling and simulation modelling tools to assess the performance of a proprietary single house grey water recycling system…

Graywater (Sustainable Building Sourcebook)   In certain parts of Austin, difficult conditions such as steep slopes, poor soil percolation qualities, close proximity to lakes, or other problems may require the services of a licensed Professional Engineer. However, in areas without unusual conditions, a sub-surface greywater system can be approved…. Greywater systems are modifications of septic system technology and, thereby, use components standard to septic systems. The primary modification is the location of the drainfield in the root zone of plants making the greywater most useful as irrigation….…

Grey Guidelines (Sustainable Building Sourcebook)

Wastewater systems that incorporate greywater irrigation should permit flexibility in response to occupant's wastewater patterns, seasonal variations in demand for irrigation, and weather. This system would entail a separate sewer or septic connected blackwater system that is linked to the greywater system for overflow and other backup purposes. However, the fact that blackwater can occasionally be generated by greywater sources is less of a concern in sub-surface systems than in above-ground systems…

Using Household Gray Water - July 11, 2001, Jeff Schalau, Backyard Gardener  In addition to the sources of water that are allowable for use, the new regulations require that household gray water systems comply with the following rules: 1) your house may not be on a flood plain; 2) the gray water may only be used for….…

Envirosink (The Grey Water Recycling System), helping America save water since 1995   Envirosink allows you to conserve the 'light' gray water from your kitchen. Envirosink is the only system that allows catchment of water at the kitchen sink -- to help fill your rain barrel in the dry


Water Conservation in the Home   We can no longer take water for granted! So here's some tips for saving water - and using it more wisely…contains tips on water conservation and grey water qualities and uses…

US-EPA. Information Package: Greywater. 1996. NSFC, Morgantown, USA.

Greywater, What it is ... ways to treat it & use it  There are very significant distinctions between greywater and toilet residues; for how these wastewaters should be treated /managed and why they should not be mixed together…

Sixth International Permaculture Conference & Convergence, Perth & Bridgetown, Western Australia, September 27 to October 7, 1996    Conference Proceedings Chapter Eight - Technology Stream, Greywater Reuse: Some Options For Western Australia, Martin Anda, Dr. Goen Ho, Dr. Kuruvilla Mathew (Australia)

Conference Proceedings Chapter Eight – Technology Stream

Greywater Re-Use:  Hardware, Health, Environment And The Law, Glenn Marshall (Australia)

Gray Water Reuse studied in California Homes, September 1996, U.S. Water News Online, SACRAMENTO, Calif.  Under the program, a family or housing unit uses its own wastewater -- excluding sewage -- to irrigate its own landscape, thus reducing water consumption and saving considerably on water bills…

Grey Water  Recycling examples…

Texas Water Reuse Update, By H. W. Hoffman P.E., December, 1998   Gray water reuse has been occurring for years. Running the washing machine water on the lawn was a common practice at one time, but since the 1950's, most plumbing codes have required all wastewater sources to be sewered because of the potential to cause nuisance problems such as stagnant water and sites for mosquito breeding. Gray water can also carry pathogens…

Conserving Water: Rainbarrels, Cisterns and Gray Water (Cooperative Extension-Clallam County)  However, use of gray water is illegal in Washington State, although some new regulations are under consideration which might permit strictly controlled use. The concern is that waste water frequently contains as much bacteria and fecal coliform as "black water" from toilets. Indiscriminate use might contaminate soils, garden produce, and surface water…

Florida Water Conservation Initiative: Conservation Alternatives includes an overview of initiatives and projects being implemented for agriculture and in-door water use

Green Design (New Buffalo Convention Center)   Design and construction practices that significantly reduce or eliminate the impact of buildings on the environment and occupants….including Gray Water Recycling: reduction of water use through the provision of a two-pipe supply system in restrooms may be applicable…

Grey Water Recovery, Navy Energy Showcase (The Cornerstone Project, Building 850 Technologies Overview)   Water from bathroom lavatories and rain run-off is collected through a separate plumbing system and stored in an underground tank. This water is then used to flush toilets and urinals….…

Home Use of Graywater, Rainwater Conserves Water--and May Save Money by Joe Gelt   grey water definition, pros and cons, systems, regulations in Arizona, plus a look at California’s gray water policy…..

State Regulations (US), Compiled in 1999: Composting Toilets, Graywater Systems, and Constructed Wetlands

A Compendium of Greywater Mistakes and Misinformation on the Web (Oasis Design)  The most common greywater errors and the preferred alternatives; part of an ongoing effort to reduce, reuse or recycle the tidal wave of greywater misinformation on the web…

Needed Improvements to California's Greywater Law (Oasis Design)  California's new greywater law is an important step and certainly as well done as was politically possible. However, it's a step not quite in the right direction, which is unfortunate as it is being emulated all over the US and the world.  Here's a list of needed improvements, excerpted from the Builder's Greywater Guide, which also includes the full text of the law with annotations directly in the text describing the implications of each section. 

Greywater Central (Oasis Design)

Accurate, Up-to-Date Information on Greywater Treatment and Reuse Systems …

The Builder's Greywater Guide, by Art Ludwig    Installation of Greywater Systems in New Construction and Remodeling, includes text of new greywater law, a supplement to the book "Create an Oasis with Greywater"….

Microbial Quality of Recycled Household Graywater (Session 59/Q., Paper Q-88), by Lisa Casanova (100th General Meeting of the American Society for Microbiology, May 21-25, 2000, Los Angeles, California)    The microbial quality was assessed mainly by looking for fecal coliforms and Escherichia coli. Graywater was found to have fecal coliforms and E. coli, which demonstrate contamination by fecal matter, possibly from handwashing, laundering of clothes, and the kitchen sink. The greatest source of contamination was found to be the kitchen sink. These findings support several recommendations for restricting graywater sources and human contact with graywater in order to minimize the health risks…


Graywater Use Still a Gray Area


Gray water recycling called next wave, by: Roberta Holland (Boston Business Journal)    Area companies are tapping into the technology of reusing water for everything from laundry to landscaping, as cities and towns struggle with increasing demands on their water supplies. ..…

Greywater Recycling and Irrigation Systems   The ECO Design Greywater Recycling System (GRS) is a low cost and low maintenance greywater treatment and distribution system for irrigating the plants and trees in your garden….…


Domestic Wastewater Management Series


Differentiating Management of Water Resources and Waste in Urban Areas, by: Ralf Otterpohl, Andrea Albold and Martin Oldenburg, Germany

New integrated sanitation and waste management systems will mostly have to respect different qualities of matter from human settlements: Blackwater with biowaste, graywater, stormwater runoff and non-biodegradable waste …

Safe Use of Household Greywater, Guide M-106. Revised by Marsha Duttle, Extension Research Assistant -College of Agriculture & Home Economics- New Mexico State University

The New Mexico Environment Department and the Construction Industries Division govern liquid waste disposal in New Mexico, and issue permits for approved systems. Greywater use is restricted by the Liquid Waste Disposal Regulations (LWDR), but the Environment Department can grant a variance if the applicant shows that:…


How to Conserve Water and Use It Effectively   This chapter explores a number of water use efficiency practices. The practices have been evaluated by many researchers,…

Regional Approaches to Efficient Water Uses: Tales From the Trenches This chapter presents a sampling of programs throughout the Nation that use one or more water conservation and use efficiency practices….…

PRESENT TECHNOLOGICAL OPTIONS FOR WATER USE AND TREATMENT IN THE CONTEXT OF THE ECOLOGICAL INTEGRITY APPROACH, UWEP Occasional Paper, Herbert Aalbers & Minne J. Sietzema, December 1999   With the expected increasing water scarcity the prices of water may increase in the near future; a development that will increase the feasibility of water saving technologies…….. Another aspect of the ecological integrity approach is to find out what options there are at the "end-of-the-pipe"…


Reuse Options for Household Wastewater [pdf](Domestic Wastewater Management Series), Information Bulletin, November 2001


Proceedings of Technical Expert Consultation on Appropriate & Innovative Wastewater Management for Small Communities in Countries of EMR, 6-9 November 2000, Amman, Jordan (WHO/CEHA papers and presentations of unique relevance (middle east & north africa region)The Impact of Reduced Wastewater Generation through Implementation of Water Saving Devices, by: G. Moore. Presented at: WHO/CEHA Expert Consultation on Innovative Wastewater Management for Small Communities, Nov.2000, WHO/CEHA, Amman, Jordan


What is Recycled Water? 

Collection of information on wastewater & greywater recycle and reuse …


1 What is recycled water?  Melbourne Water's quarterly magazine


Greywater Reuse in Sewered Single Domestic Premises, April 2000. [16 pages, pdf]


Innovations from Scandinavia: Increasing the Potential for Reuse, Sarah West, On-site ‘01 Conference, September 2001. [pdf]


Why Not Reuse?  How about a reuse system for your home? Most components to build simple reuse systems using bath or laundry water are available from swimming pool supply houses or hardware stores. Local building codes will have to be changed in some Texas cities before such reuse systems would be allowed. State and federal laws, however, do not discourage home reuse systems. New federal laws requiring water conservation will probably even speed the acceptance of home reuse…


New Water Reuse Technology Reduces Water Consumption by 95%, Wastewater Pollution by 100% and Recycles All Household Water  Equaris Corporation, today announced the results of twenty-five years of development of its' recently patented Blackwater Biomatter Resequencing Converter, Greywater Treatment System and Total Household Water/Wastewater Filtration, Disinfection Recycling Technology….

Alternative Wastewater Systems  Current systems squander greywater by mixing it with blackwater (7.2 Greywater Recycling, pdf format)


Water and Wastewater (Building Design)  Because the site is served by the local sewerage system, regulations prohibited the treatment of blackwater on the site…


The RUCK System   In the RUCK system the household's greywater (washwater) and blackwater (toilet and kitchen sink wastes) are plumbed separately and flow to separate septic tanks (Figure 1). The blackwater flows from the septic tank to the aerobic RUCK filter where it is nitrified and then flows to the anaerobic greywater septic tank for denitrification…


On-Site Sewage Management System Options (52 pages, pdf)

Very useful document (wastewater minimization, wastewater characteristics, system options)…

Greywater Reuse in Urban Areas  (110 pages, pfd)


Investigation on Reuse Potential of Laundry Water for Household Garden Irrigation in Toowoomba  . (pdf format, 115 pages)


Wastewater and stormwater treatment, (ENVIRONMENTALLY SOUND TECHNOLOGIES in wastewater treatment for the implementation of the UNEP GLOBAL PROGRAMME OF ACTION (GPA) “GUIDANCE ON MUNICIPAL WASTEWATER”)

Blackwater to Holding Tank and Greywater to Septic Tank 

With this type of system, the residential plumbing system is separated, with the blackwater (toilet wastewater) portion of the wastestream stored in a holding tank for routine pumping and transport offsite for treatment and disposal. The greywater portion of the wastestream (wastewater from all non-toilet plumbing fixtures) is collected in the building's plumbing system and conveyed outside by gravity to a buried septic tank…

Scenarios for Sound Practices - Sanitation Alternatives Considered in SANEX  For a low population density and where land is available around dwellings, on-site systems with on-site reuse provide householders with options that are a function of water availability, toilet type and desired reuse of blackwater and greywater…… For a high population density, community ablutions blocks with payment for use can work well…


pal@grey-water.hu                           www.grey-water.hu