Whether you spell it “gray” or “grey,” it’s still looks dingy – at least when it’s headed down the drain. But it could be part of a long-term solution to California’s water woes.
“Gray water” (or “greywater,” as it is often called) is that soapy liquid left over from baths, showers and laundry. It started as drinkable water and can end up with a second use. That could be irrigating your lawn and garden or, with the right plumbing, flushing your toilets.
Repurposing this wastewater can help homeowners dramatically cut overall water use, said Bob Hitchner of Nexus eWater. “People are trying to cut 25 to 36 percent now (under current state mandates),” he noted. “But this could save 60 percent, just by recycling your gray water on-site.”
Nexus eWater, an American company born in drought-plagued Australia, is working with new home developers in California to make gray water recycling as common as laundry rooms. Its integrated system recently was certified by the state of California as the first such product that met the state’s plumbing code standards for treated gray water.
Recently, Hitchner demonstrated the “NexTreater” for local water district experts at KB Home’s “Double ZeroHouse 3.0” model home in the new Fiora subdivision in Blackstone, a 990-acre master-planned community in El Dorado Hills. (The Double ZeroHouse is open to the public for tours daily, too.)
This development already had a head start on recycling water. El Dorado Hills uses two wastewater treatment plants to recycle water for irrigation of lawns and landscapes. Purple pipes, which are used to differentiate recycled or gray water from drinking water, are built into the city’s new homes for landscape irrigation.
The NexTreater takes it a step further. The wastewater is treated (and stored) on-site and can be used for toilet flushing, too. Toilets represent 25 percent of indoor water use.
It’s the only fully automatic home water recycler on the market today, Hitchner said. Costing about $10,000 installed, the current hardware is designed for new construction only.
“The purple pipes are totally separate from other plumbing,” Hitchner noted. “Retrofits can be very expensive, especially if the home is (built) on a slab foundation. But we’re working on it.”
In addition, the Nexus system also captures heat while purifying gray water and uses that energy to heat clean water for the home.
Two-thirds of indoor water use goes toward cleaning either people or clothes, Hitchner explained. For a family of four, that adds up to 40,000 to 50,000 gallons a year. Recycling gray water gives a second life to 2 out of every 3 gallons. Plants can’t tell the difference after the soap and scum are removed.
Inside a unit not much bigger than a gym locker, the gray water is cleaned, 10 gallons at a time. Soap, detergent and other solids are bubbled out. Then, ultraviolet light purifies the water, which goes into an underground holding tank. The system can process up to 200 gallons day.
“Once it’s treated, it looks and smells just like drinking water and can be used for irrigation or toilet purposes,” Hitchner said. “The UV light kills any pathogens.”
Gray water is getting a second look from a lot of Californians who previously ignored its possibilities, noted the water district experts. Recycled water could stretch limited reserves.
“We need to look for other ways to keep using our water while we have our hands on it,” said Vicki Sacksteder, water resources analyst for the San Juan Water District.
Gray water is not a new concept; since the 1970s, creative homeowners have tried to capture it with jury-rigged devices to move the sudsy stuff from the tub to the garden. These low-tech systems usually are nicknamed “laundry to landscape” since redirecting the clothes washer’s waste line is easier than the bathtub drain.
This homemade approach can be problematic, according to Tom Wood, one of the inventors of the Nexus system. By state law, untreated gray water must be used within 24 hours. It can only be used for landscape irrigation by subsurface distribution, such as drip systems; you can’t just run a hose from the washing machine to the lawn in California.
By law, untreated gray water cannot be used to irrigate edible root vegetables. In addition, the soaps and detergents in that gray water can be toxic to plants.
“This makes it impractical for a lot of people,” Wood said. “You create gray water every day. With treated gray water, you can keep it until you need it.”
Treated gray water, such as that produced by this system, can be stored indefinitely for reuse. It can be connected to conventional irrigation systems and used to water vegetables and fruit trees. And it works in toilets, too.
As California continues to grapple with water issues, expect to see a lot more purple pipes. That treated gray water can look like a crystal clear option for a thirsty garden.