Gray water systems in Brooklyn brownstones, where you collect shower, bath, sink and clothes washer water in a tank and then pass the gray water back to the toilets when you flush, essentially eliminating any use of water for toilets, makes a lot of sense.

I am really into gray water systems of this type here in Brooklyn NY  because it reduces the load on the old sewer system. Whenever it rains the sewers overflow and all the nasty sewage goes into the rivers and canals. Near the Brooklyn Green Show House the water overflows into the Gowanus Canal, which reeks of sewage after each rain (not to mention is full of nasty floating objects).

Gray water also to a  small degree reduces the already cheap water bill (compared to other places in the US). But hey it is still money savings.

Up to now Eco Brooklyn has installed the Brac Gray Water System from Canada. It is a very good system and is what we display in the Eco Brooklyn show house.

The drawbacks are that it comes from Canada and it is prefabricated. It is also not cheap. To meet these issues we have developed an Eco Brooklyn Gray Water System in an effort to reduce the cost of the materials and to keep the work local.

We are very happy with this solution because it gives us more control over the design process. Each home has different needs and available storage space for a unit. Brownstones are a very tight fit and designing for the space makes a lot of sense.

We also need a very quiet unit due to the close quarters of a Brownstone. The Brac system is built for the average home, which invariably has more space than a Brownstone, so a quiet unit was not imperative.

But for homes outside of the New York area we still think the Brac System is one of the best options.

Here is some background information on gray water systems that a colleague in Australia sent me:

This Eco House in Sydney is very interesting because it is essentially the same as a Brooklyn brownstone and shows what is possible. It is almost completely self sufficient. One of their main things, amoung many interesting things, is gray water.

Here is a very good detail of what gray water is and how to use it. The document if from New South Wales in Australia.

From the doc:

What is Greywater?
Greywater is wastewater generated by the use of a:
· hand basin,
· shower,
· bath,
· spa bath,
· clothes washing machine,
· laundry tub,
· kitchen sink.
· dishwasher.

Although they point out that a kitchen sink is borderline and personally I consider it too fertile with food scraps to be gray water, although it isn’t exactly black water either.

Also from the doc are numbers for how much greywater is generated by households. Their numbers are for NSW Australia in liters. There are very roughly four liters to a gallon so divide the numbers by 4 to get gallons.

household gray water

You will notice that toilets use one third the water in a house. So a gray water system that feeds the toilets reduces a house water usage by one third. That is a hell of a lot of water savings.

This is also an average house and not an eco house. The average house uses 186 liters of water a day to flush a toilet. That is almost 50 gallons. Or 30 daily flushes of a normal 1.6 gallon toilet.

An eco house would use a lot less. The Brooklyn show house for example has 1.1 gallon/flush toilets which if you use the average of 30 dayly flushes would translate into only 33 gallons per day of toilet water.

This means the Eco Brooklyn show house uses 40% less water for their toilets. Not that it maters since the toilet water is gray water….although it is good the toilets consume less gray water because there is less gray water available since the house creates a lot less gray water than a normal house due to the high efficiency clothes washer and water fixtures :).

It all gets a little circular and a bit confusing. The bottom line is that the Eco Brooklyn show house uses less water and creates less waste water. Both good things.

Here is another brochure again from Australia. From their brochure:

7 Reasons why Grey is the new Green
1. Greywater is produced everyday.
2. Demand on precious drinking water is reduced by 40%.
3. Reduced chlorine discharge to the environment.
4. Treated greywater is good for your garden. Your garden is good for the environment.
5. The system is available today. (I am not sure why this makes it green, but anyway)
6. Infrastructure and energy costs are reduced.
7. If every new or renovated house in Australia recycled their greywater, savings each year would be adequate to meet the drinking water requirement of Geelong. (I have no idea where Geelong is but I presume they drink a lot of water)

Some of the best resources come from unsurprisingly one of the most water starved areas of the US: Arizona.

The Water Conservation Alliance of Southern Arizona knows their stuff when it comes to saving water. They have a good gray water study which annoyingly is only available if you email and ask them for it. Although their research is not really applicable to New York gray water situations it is nonetheless informative.

Here is a good breakdown of Arizona Gray Water Law from which is interesting to me insomuch as it is a good template for the still underdeveloped New York Gray Water Law. Due to our seeming abundance of water on the East Coast we have not had a need to really look into gray water as much as Arizona and California. But in my opinion water conservation is clearly a global issue no mater how much water is in your back yard. is a very useful site. Many regard it as one of the best in gray water and water conservation in general. You can spend hours learning from the site.

And lastly there is which of course wins the prize for best domain name. Despite that it is a very small site. But what is there is very valuable info and woth spending a few minutes reading.