House & Home

Recycling Water Is a Gray Area

Posted November 26, 2007
Updated November 27, 2007

— Rain-deprived homeowners in the nation's Southeast are exploring every option available for saving their lawns during one of the worst droughts on record - including using recycled waste water for the garden.

There's just one problem with that act of conservation: It's restricted or outlawed in many areas.

"We're using our bathwater and shower water to flush toilets. We were using it to water our trees but we stopped doing that because we learned it was basically against the law," said Stacy Murphy of Durham, North Carolina "The trees have gone dormant, anyway."

"Gray water" is the discharge from a kitchen sink, laundry, dishwasher, bathtub or shower stall. It's not clean enough to drink, but it contains less nitrogen and fewer pathogens than "black water" or toilet waste.

Still, it is capable of carrying enough bacteria to trigger typhoid fever, dysentery, hepatitis and other gastrointestinal or viral problems. Laura Leonard, a spokeswoman for the North Carolina Division of Environmental Health, said gray water can have about the same amount of fecal coliform bacteria as whole wastewater.

Gray water is often banned for irrigation for public health reasons. But some have questioned the ban on plant watering for ornamental gardens.

"When the laws were drawn up some decades ago, it was more out of public health concerns. But cholera epidemics are almost a thing of the past," says Murphy, who has already cut corners as much as possible. She and her husband don't wash their cars and have cut back on washing their bed linens. And now they've stopped watering their plants.

Gray water does little harm if it isn't sprayed directly on edible plants and foliage, said Kim Coder, an extension forester with the University of Georgia.

"It's hard to find a down side at all when you spray it on ornamental trees and shrubs - especially if you know what went into it," he said. "If you're simply washing your hands or using dishwasher detergent, the impurities become pretty diluted by the time they flow from the house."

Coder participated in a pre-Thanksgiving Day meeting called to determine if Georgia's gray water policies should be relaxed in the midst of a lingering drought. While public safety trumps conservation, he said officials should find ways to reduce risk and still conserve.

"If it's a matter of losing a few begonias by not watering, that's not a big deal. You can always replace them," he said. "But if you lose a sizable tree from your front yard, it will be three generations before you see its like again.

"That kind of thing might make it worth taking another look at our half-century-old regulations to see if gray water can be used (for irrigation)."


Check your local ordinances to see if gray water can be used in your area. The City of Gilroy, California, has published these safety guidelines for gray water use during prolonged dry periods:

-- Do not connect your gray water drainage pipes to any part of your interior or exterior plumbing system. This could result in dangerous gray water backflow into your drinking water supply.

-- Gray water should not be used on root crops and such low-growing food crops as carrots, radishes, onions, lettuce and strawberries. Gray water may safely be used for taller non-root crops including beans, corn and tomatoes if edible portions of the plant aren't targeted. Gray water also may be used for turf grass, tree and shrub irrigation.

-- Ensure that any gray water used for irrigation soaks quickly into the ground. Avoid creating ponds or generating runoff.

-- Do not irrigate with gray water if it was used for laundering diapers or clothing and bedding coming from someone who was ill.


University of Georgia College of Agricultural and Environmental Services fact sheet:


You can contact Dean Fosdick at deanfosdick(at)


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