While researching green ideas for my house, Graywater plumbing was among the top of my list.
Greywater, sometimes called graywater, or sullage, is considered non-industrial waste water generated from domestic processes such as clothes washing, showering/bathing. Greywater comprises of 50-80% of residential waste water. Greywater is distinct from blackwater in the amount of and composition of it’s chemical and biological contaminants. For example, water discharge from the dishwasher or kitchen sinks has an increased amount of food and contaminants and is considered dark or blackwater.
When I was ready to build my house, I phoned five different plumbing companies, asking if they were familiar with grey water systems or simple grey water plumbing. The first 4 companies gave me a song and dance about special codes by the city, all of the cost, blah blah blah. The last company I called was actually EXCITED about greywater plumbing. The owner of the plumbing company told me he would draw it up and we talked at length about the fact that very few people actually think about it. He showed me a pamphlet containing the county’s ” grey water use requirements” which is listed below: ( These requirements cover most of Southern Arizona) You can also click on this link and view it as well: www.azdeq.gov
1. Avoid human contact with gray water.
2. You may use gray water for household gardening, composting, and lawn and landscape irrigation, but it should not run off of your property.
3. Do not surface irrigate any plants that produce food, except for citrus or nut trees.
4. Use only flood or drip irrigation to water lawns and landscaping. Spraying gray water is prohibited.
5. It cannot drain into a wash or drainage way.
6. Gray water may only be used in locations where groundwater is at least 5 feet below the surface. (Funny!)
7. Label gray water pipes under pressure if confusion between gray water and drinking water pipes is possible
8. Cover, seal and secure storage tanks to restrict access by small rodents and to control disease carrying insects.
9. Hazardous chemicals such as anti-freeze, mothballs, and solvents cannot be in gray water. Do not include wash water from greasy or oily rags in your gray water
10. Gray water from washing diapers or other infectious garments must be discharged to a residential sewer or other waste water facility, or the water can be disinfected prior to it’s use.
11.Surface accumulation must be kept to a minimum.
12. Should a back-up occur, gray water must be disposed into your normal waste water drain system.
13. If you have a septic or other on-site waste water disposal system, your gray water use does not change that system’s design requirements.
Now, I elected to use a “passive” system, which does not require pumps, filtration systems or the likes. I have two zones where one half of the house discharges water to one side of the yard along with the washing machine, an the master bathroom and powder room discharges on the opposite side. I do have a valve that will allow me to direct the gray water into my septic tank if, for instance I clean the shower with a partially caustic chemical. There are no pumps, just pipes that I direct to the plants in my yard. I’m sure I will eventually add a somewhat unsophisticated pump and filtration device to irrigate my plants, and I am working on a design for that as I write. As far as the septic system we have for our house, we still were required to have the same size tank for the house as if we were not using gray water.
In reading over the ADEQ reclaimed water pamphlet, there is a small paragraph on the pamphlet that says, ” Residents must adhere to the guidelines for reclaimed water type 1 general permit. A type 1 general permit requires NO formal notification to the department, NO review or design approval, and NO public notice, reporting or renewal.
Now, lets talk about houses that are pre-existing. Your best bet for a grey water conversion would be with an older home that has a raised foundation. The plumbing pipes are accessible ( for the most part ) and can be converted. The other 90 % of the homes have slabs, and is cost prohibitive to retrofit to gray water. The only homes I’ve seen have been where the laundry is outside in a carport closet and is the only grey water used, and can be done much more easily.
So far my plants love it, my water bill is lower than most, and I feel like I’m doing something to help the drought!
Posted by tlcpro 