Save green: Use your gray water

Published on November 1, 2009

by Jacqueline A. Soule, Ph.D.

Not so long ago, the three Rs were reading, 'riting and 'rithmatic. Today, it's more likely to be reduce, reuse and recycle. One great way to apply this is to reuse gray water from your home in the landscape.

Gray water is not gray from sewerage. It's gray from the bathwater of grubby children or a washer load of clothing. Not only is gray water safe, its use is encouraged in some areas. However, be sure to check your local ordinances before you start reusing your household water.

Using gray water saves money when watering a lush landscape or plants that appreciate the extra drink such as and Canna (seen here).
Photo courtesy of Jacqueline A. Soule, Ph.D

Reusing water isn't a new idea. In pioneer times, household water was arduously acquired, so of course, it was reused. Dishpans were emptied on dooryard herbs, clothes washing was done outdoors where the water could easily be recycled, and bathwater was tipped out in the garden.

But cities grew and people became fearful of the germs such water might harbor. Beginning in the late 1800s, many cities and states passed ordinances prohibiting gray water use.

Until recently, there were no scientific studies regarding the safety of gray water. In the late 1990s, a study was conducted under the auspices of the Arizona Department of Environmental Quality which included stored and direct use of gray water from laundry rooms, kitchens and bathrooms. The study, which lasted more than a year, included homes near city wells and different soil types.

The DEQ report helped Arizona craft sensible laws for gray water use and has been used as a model for other areas throughout the West. Essentially all household gray water was found to be safe, except that kitchen water could include food waste that could harbor harmful bacteria.

Even for those who may live in a wetter climate, gray water can help save money — especially in drought years. If you own a septic system, reducing the amount of water and soap allows the normal septic bacteria to more easily break down waste. Thus, the need for periodic pumping is reduced. Less effluent in any sewer system reduces maintenance costs. Gray water saves city homeowners money on their water bills and us taxpayers footing the bill for wastewater treatment.

And don't worry about your plants — average gray water won't bother them. Most hand and body soaps, as well as shampoos, are as safe for plants and soil as they are for your body. Err on the side of caution however, and avoid using gray water on vegetables. Also note that gray water with soap is alkaline, so avoid its use on seedlings or acid-loving plants.

In most cases, the easiest way to start reusing your gray water is to use the water from a clothes washer. Securely attach a discharge pipe or tube to the discharge hose of your washer. A discharge tube is a type of wide, soft plastic pipe that lays flat unless water is running through it and is available at hardware stores. This type of tubing requires a fairly straight path to empty. If you have corners, you'll need to use a rigid system, such as PVC pipe.

With a little creativity, and unless local laws prohibit it, you can apply the three Rs to your household water.

Jacqueline A. Soule, Ph.D., is a botanist, writer and educator. A member of the Garden Writers Association, she writes gardening columns for a number of newspapers throughout the Southwest. A self-avowed "Darwinistic" gardener, Jacqueline prefers plants that need as little care as possible while providing color, texture and movement in the landscape.