Gray water is the waste water from dishwasher’s, washing machines, sinks, bathtubs, and showers of homes and commercial buildings.
As a Master Plumber I have never installed a gray water system for a house nor a commercial building but I know how they work and have installed systems similar to gray water recycling systems. We in the United States have not yet as I’m aware of made an attempt to conserve water in this way for a community or for commercial building’s. I know several home owners who have custom made homes and have added a proper gray water recycling system to conserve water and help save our environment.
Some time in the near future in my opinion cities and states will realize how easy it is to conserve water with a grey water recycling system and will probably require one in every new home built in America.
Each state has their own plumbing code in regards to gray water and how it can be used or discharged. In the state of Colorado our plumbing code “International Plumbing Code” allows gray water to be discharged to an approved grey water system for flushing of water closets and urinals or for subsurface landscape irrigation.
Motor-homes, travel trailers, fifth wheels, and other recreational vehicles use separate holding tanks, one for grey water and the other for black-water ( waste water from water closets). See a picture’s
Grey water holding tank under a travel trailer
Black-water holding tank under travel trailer..
The International Plumbing Code allows two ways to install a gray water recycling system.
1. Above- ground with drain, waste and a venting system.
2. Underground building drainage and a proper venting system.
There are many other plumbing code requirements for a proper grey water recycling system like: A gas-tight vessel, corrosion-resistant, the reservoir constructed of durable nonabsorbent material, filtration, full open valve, disinfectants, food grade vegetable colored dye, an overflow pipe off the collection tank indirectly connected to the sanitary drainage system and a few other plumbing code requirements.
See drawings of the two types of grey water recycling systems per the International plumbing code.
The above drawing is for an irrigation system.
The above drawing is how you would plumb the grey water recycling system to flush your toilets in place of fresh water from the water department.
I hope this information helped to understand how and what grey water is.
Take a look at my new book available on Amazon.com called “Flush Your Plumbing Troubles Down The Toilet” for those who may have an interest on other plumbing information.