Water Conservation Alliance of Southern Arizona
Resedential Graywater Reuse Study - Fact Sheet
Back to Residential Graywater Reuse Study
The following text could form the basis for a brochure to inform the interested public about the pending regulations from ADEQ regarding residential graywater reuse, should they become law. This fact sheet is consistent with the findings of the study and the proposed rules, but will not be published for distribution. It has been developed in fulfillment of the provisions of the contract with ADWR for partial funding of the graywater study.
What is graywater?
Graywater is the waste water from your washing machine, bathroom sink, bathtub, and shower. Kitchen sink and dishwasher water is not to be considered graywater. Water from your toilet is black water.
Why reuse graywater?
Graywater represents the largest potential source of water savings for your residence. The reuse of your graywater for landscape irrigation makes a powerful contribution toward the reduction of potable water use. You can generate from30,000 to 50,000 gallons of graywater at your home each year that is free landscape irrigation water.
Do I need a permit to use my Graywater?
ADWR estimates 35 gallons of graywater is generated each day per person in new construction, increasing to approximately 46 gallons each day per person in existing homes. You can calculate how much graywater your family will generate by multiplying the number of people in your residence by 35 if you are just moving into a new home, and by 46 if you are living in an existing dwelling.
If you calculate that your family will generate over 400 gallons of graywater a day, you must notify Pima County Department of Environmental Quality, 740-3340, to obtain a permit that conforms to Appendix G of the Uniform Plumbing Code.
If your family will generate less than 400 gallons of graywater a day, notification is not required but you need to heed the following information on order to protect the health and safety of you, your family and your community.
How do I safely use my Graywater?
At my home
- Your residence must lie outside of the active flood plain.
- The graywater must originate from your residence.
- Your graywater must only be used for landscape irrigation at your residence.
- Your graywater must never be allowed to leave your property.
My system
- Your graywater system needs to have a way to discharge to the septic or sewer system in the event of plugging or any other problem with your graywater quality or the system itself.
- Piping should be PVC or ABS.
- Make sure your graywater storage has a secure cover for safety and mosquito control.
- If above ground, be sure your graywater storage is childproof.
Do's...
- Your irrigation system should be operated to efficiently provide sufficient water to your plants while minimizing loss from deep percolation beyond the root zone.
- Filter your graywater with something as simple as a stocking to trap hair and lint.
- Regularly check your graywater system to be sure it is functioning properly.
- Frequently check your plants that are graywater irrigated for signs of over watering or stress from high organic content in the water.
- Check the publication Graywater and Your Detergent for information about ingredients in laundry products that may affect the plants you are irrigating.
- Use your graywater for flood or drip irrigation only.
- Divert your graywater to your sewer or septic system when laundering diapers or dying clothes.
And Don'ts...
- Don't drink your graywater.
- Don't use water from the laundering of diapers because the bacterial contamination is too high and is a health risk.
- Don't use water that contains hazardous chemicals such as those used for cleaning car parts, washing of greasy or oily rags, disposal of solutions from home photo labs or similar hobby activities.
- Don't allow your graywater to pond beyond what is necessary to effectively irrigate your plants. Standing water increases health risks and provides breeding opportunities for mosquitos.
- Don't use your graywater for spray irrigation.
- Don't irrigate root or leaf crops (ie carrots, lettuce) intended for human consumption.
- Don't reuse your graywater if any family member has an infectious disease such as diarrhea, hepatitis or internal parasites.