Next Step in Sustainability will be Requiring Homes to Recycle Water

Lancaster, California was one of thefirst municipalities to push the envelope on sustainability by requiring homes to be solar-ready, as part of Mayor RexParris’ goal of becoming a net-zero city.

Parris has now takenhis sustainability goals one step further by addressing water consumption innew homes. Beginning in 2015, all new residential construction in Lancaster, acity of approximately 158,000, will be required to have “recycle-ready”plumbing.

Nexus eWater is aLancaster, Calif.-based startup that hopes to benefit from this novellegislation. The company has a system that recycles the gray water in the home,as well as the heat in that water, and recycles it for non-potable uses, suchas for irrigation or toilet water. More than 80 percent of the water used inthe typical home is not used for drinking.

The need forbuilt-in water conservation is growing, especially in the parched Western U.S.California is now in its third year of sustained drought. The drought haspushed cities to strengthen efficiency mandates, and has alsojeopardized hydropowerresourcesand wateravailable for thermal cooling. Ongoing water issues are forcing municipalitiesto examine every point in the water system, in some cases compelling themto invest in smart water metersandupgraded water-efficiency programs.

In homes, recyclinggray water could be one of the best ways to slash water use. Nexus can recover2 of every 3 gallons of a home’s gray water, which comes from sinks, laundryand baths. Not only does the system reuse gray water, but it can also recoverthe heat from the water to be reused by the water heater, according to RalphPetroff, co-founder and CEO of Nexus eWater. He saidthe system can cut the total amount of water used by a home by about one-third.

The cost of thesystem on new construction is less than $10,000, although it can also beinstalled as a retrofit. Currently, Nexus is working with KB Homes on a seriesof net-zero homes.

Engineers inAustralia developed the system, although the focus is on the U.S. market, whichhas a far larger new homes market than does Australia.

The system involvesplumbing that diverts water from gray water sources to an underground 75-gallondrum. Within the drum, bubbles are injected into the water to make a frothy mixfrom which dirt and oil are lifted to the top and removed. The water is thenrun through a carbon filter and blasted with UV light, and then run throughanother filter for good measure.

For systems thatalso recover heat from the water, which is usually warm from being used inshowers or laundry, a heat exchanger is added. The heat exchanger transfers theenergy back to Nexus’ hot water heater. Nexus says it can cut hot water energyuse by 75 percent. Water heating is a significant energy load in the house,accounting for about 14 percent to 25 percent of total energy use in typicalhomes, according to the U.S. Environmental Protection Agency.

The system might notmake sense for most existing homes because of the upfront cost, but for newhomes, the payback on new construction can be immediate for builders. Petroffsaid that the cost of water and sewer tie-ins could be up to $30,000.

He added that houseswith his company’s technology only generate one-third as much sewage as anaverage home, and about one-sixth the peak sewage of new, water-efficienthomes. The result for builders is that they can build more homes for the samesewer connection fee.

It’s still earlydays for Nexus, which will likely need far more municipalities to pass lawssimilar to Lancaster’s in order to get market traction. Higher water priceswould also make a difference, not only for Nexus, but for all water-efficiencytechnologies that are ready for prime time but have not yet achieved the pricesignals in the market that they need in order to be widely implemented.

Recycling watercould also become the norm on a much larger scale for drought-ridden regions.San Diego, for instance, just approved a measure to turn its wastewater into drinking water.