Using Gray Water

greywateringcan“Gray water” refers to household cleaning water harvested for use on plants. Typical sources are the water used for bathing, washing dishes and washing clothes.

It is very important to use appropriate detergents and soaps in gray water collected from bathing, washing dishes and washing clothes. Use only low phosphate soaps and do not use bleaches or other cleaning agents.

For the long-term health of the soil, alternate waterings between gray water and potable water or collected rainwater.

Fertilize the soil with micro-biologically active agents such as organic compost and composted manure to break down any unwanted chemical agents in the gray water.

Simple ways to collect gray water:

  • When bathing, place a bucket or pan on the shower floor to collect water. After showering, empty the bucket into a larger container such as a  plastic trash can, then fill a watering can from that. Or plug the tub drain and bail out the water after showering, or use a pump and hose.
  • Use a plastic tub to wash and rinse dishes, then empty it onto plants or into a collection reservoir.
  • Extend the drain hose from the washing machine to a collection reservoir. Take water as needed from the tank. Or direct the drain hose into a bucket and carry the full bucket to the plants. Be sure the bucket is big enough, and be sure to monitor the drain cycle to avoid overflowing.

Install a Whole House System
A gray water system can be built into a house during construction or added to an existing home with plumbing accessed via a crawl space. These systems usually consist of an underground tank, a pump and separate drain lines from the bath, shower, kitchen sinks and washing machine.

Gray water systems often employ an automatic pump and float switch so that the collection tank is automatically evacuated to the outdoor watering system whenever the tank’s water level gets to a set point. On-demand systems use a manual switch or timer to control watering times.

For details about the safe use gray water be sure to read the New Mexico Environment Gray Water Regulations