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Codes are the Last Obstacle to Wider Use of Graywater in Homes

3/31/2016 | by Matt Power

Today, the technology and know-how exists to take graywater from washing machines and showers—as well as rainwater collected from roofs—and use that water to flush toilets and irrigate landscapes. That same water can be brought back into the house, treated, and used yet again. It makes a lot of sense and saves a lot of water, so why isn't it happening, or even mandated, everywhere?

"All water reuse scenarios are doable, and most of them are covered by the current code," says Doug Pushard, founder of HarvestH2o and a designer of residential water management systems. "However, there are some holes—the codes have not been integrated. The rainwater code was driven by the American Rainwater Catchment Systems Association, and the graywater code came from states doing it and publishing best practices."

An example of where adoption gets tricky is mixing graywater and rainwater in the same tank.

"This practice is not yet covered in the codes," Pushard notes."The purification is almost identical, but I have a feeling when I go to do my first one this year in Santa Fe, they will not allow the mixing of these waters. I will have to have two tanks and two filtration systems."

That adds up to extra costs for homeowners, he explains, and slower market penetration.

Builder Kim Shanahan, executive officer of the Santa Fe Area Home Builders Association, is at the forefront of water conservation efforts in the water-conscious city. Because Santa Fe adopted certain codes, the municipality is poised to take advantage of water-saving reuse. "We are going to be allowed to bring water back into the house," he says. "We adopted 2012 UPC and UMC Building Codes, as well as some chapters of the code that the State of New Mexico hasn't even adopted."

The upshot is that the municipality can bring water back into the house and reuse that water for toilet flushing and washing. "It's not unique to Santa Fe," Shanahan reminds. "Anyone using 2012 UPC and UMC Codes in their entirety can do this."

The code is quite strict. It stipulates, for example, that the water being brought back in the house, even for use in toilets, be "potable," ostensibly to protect pets or kids who happen to dip into that toilet water.

Shanahan says even this high bar can be reached, however: "We know we can treat water that has come back in the house to this higher standard than the required level, and we have the filtration and UV technology to do this. It is the future for homes: net zero energy, net zero water."


Bill Roth, president of Modern Design + Construction in Santa Fe., N.M., has been working on graywater systems for 10 years: "We don't do capture systems, just distribution systems," he says. "You take the water out of the house and to various locations. These systems aren't bombproof, but they don't have any moving parts, and you aren't treating or storing it." In the application shown here, Roth collected the water from all the fixtures of a home, and ran it via 2-inch pipe to two distribution areas in the yard. He used the calculations provided by the 2012 plumbing codes for minimum side yard capture area.

Related Tags: Performance | Codes | Sustainability | Health | Comfort/Livability | Trends