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Grey Water Central
The web's information central on all aspects of grey water systems
from the leading innovators and producers of greywater information
By Art Ludwig
Why to use grey water, how to choose, build and use grey water reuse systems, regulations, studies, science and examples. Grey water irrigation, treatment, filtration, low tech DIY systems, high tech indoor grey water reuse... For homeowners, do-it-yourselfers, regulators, inspectors, elected officials, building departments, health departments, builders, and activists. |
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The quality and credibility of our information is the key to our livelihood; 99% of our income is from information. We have developed numerous greywater reuse innovations. All have been published unpatented into the public domain. We don't have as much stake in any particular system as we have in being a trustworthy information source for all ecological design. When no greywater system is appropriate, we gain credibility by saying so. Likewise if a manufactured system is more suited than a DIY system we developed. When a better way of reusing greywater is found, we just update our information--we don't have a warehouse full of obsolete systems to be stuck with. (Our main greywater book is currently in its 19th revision!) <More about Why you can trust this info>
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Grey water informationGrey water books and DVDSystem examplesGrey water regulationGrey water research and scienceRelated topics |
What is grey water?Any washwater that has been used in the home, except water from toilets, is called grey water. Dish, shower, sink, and laundry water comprise 50-80% of residential "waste" water. This may be reused for other purposes, especially landscape irrigation. (This is the definition common in Europe and Australia. Some jurisdictions in the US exclude kitchen sink water and diaper wash water from their definition of grey water. These are most accurately defined as "dark grey water")
Why use grey water?It's a waste to irrigate with great quantities of drinking water when plants thrive on used water containing small bits of compost. Unlike a lot of ecological stopgap measures, grey water reuse is a part of the fundamental solution to many ecological problems and will probably remain essentially unchanged in the distant future. The benefits of grey water recycling include:
Healthy fruit from sanitary irrigation of edible landscape Why does grey water matter?Viewed narrowly, grey water systems don’t look that important. A low flow showerhead can save water with less effort. A septic system can treat grey water almost as well.
Many people and organizations instinctively recognize that grey water is the ideal test case for the transition to a new way of regulating and building that is appropriate to a post-peak resource, mature civilization. The US Green Building Council, the City of Santa Barbara, CA, Oregon ReCode, and SLO Green Build are among those organizations which independently chose grey water standards as the technology with which to launch their programs of regulatory reform. Is grey water reuse safe?Yes. There are eight million grey water systems in the US with 22 million users. In 60 years, there have been one billion system user-years of exposure, yet there has not been one documented case of grey water transmitted illness. (In contrast, 400 Americans get hit by lightning each year. More details, calculations and references). Is grey water legal?In practice, grey water legality is virtually never an issue for residential retrofit systems—everyone just bootlegs them. However, grey water legality is almost always an issue for permitted new construction and remodeling, unless you're in a visionary state such as Arizona, New Mexico, Texas (and soon, NV, MT, OR, and CA). For details see our Grey water policy center and Builder's Grey Water Guide (book).
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Further reading and watching from the bookstore
Create an Oasis with Grey Water (book)

Builder's Grey Water Guide (book)
New Greywater Book and Video Set: The New Create an Oasis, Builder's Greywater Guide, Principles of Ecological Design, Laundry to Landscape instructional DVD $51.80 ($13 savings)
Excerpt from our instructional Laundry to Landscape (DVD):
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