We know there’s a water crisis in drought-stricken or generally arid climates, especially in the U.S. Southwest, with stress on water supplies and rising costs or outright bans on using water to irrigate landscaping.

Out of economic and environmental concern, many people are promoting graywater reuse – diverting lightly dirtied water away from sewers and septic systems to find a second use for watering plants or flushing toilets, for example. Graywater reuse is a hot topic these days, as evidenced by the special report inside this issue of Onsite Installer (“From the Washing Machine to the Flower Garden,” by David Steinkraus).

The story outlines the efforts of Georgia Habitat for Humanity and Mercer University to build new onsite systems for low-income homeowners that incorporate experimental graywater reuse systems. Philip McCreanor, an associate professor of engineering and director of the Mercer engineering honors program, outlines the commendable efforts of his students to install and monitor these systems.

A BOON FOR BUSINESS?

Graywater reuse not only offers potential environmental and cost benefits to users, it also has the potential to add a new dimension to the services offered by onsite installers. If this practice takes hold and the operation of these systems is perfected, onsite installers could be seen as the go-to professionals to design the dispersal systems and get them in the ground. Imagine the growth opportunity for your company if suddenly many of your customers demand two systems instead of one. The upside could be enormous for contractors located in water-starved regions.

And widespread graywater reuse is not necessarily a long way off. Consider Tucson, Ariz., where the local government mandates that every new home (sewered or using an onsite system) is permitted with a diversion valve for a graywater system. Homeowners aren’t required to add the systems, but the diverting valve should start to steer many in that direction.

The water conservation movement is all well and good, but a handful of people in the onsite industry are starting to ask an interesting question: What impact will removing a large percentage of graywater have on the long-term operation of onsite systems? One of those people is Bryan Chiordi, a Phoenix-area onsite products distributor, president of the Arizona Onsite Wastewater Recycling Association and vice chairman of the Arizona Department of Environmental Quality advisory committee.

OTHER SIDE OF THE STORY

Seeing a growing interest in graywater reuse a few years ago, Chiordi wasn’t hearing a parallel discussion within the industry about the impact this would have on septic systems. He talked to many of the leading educators in the onsite industry and was told there is no definitive research data to answer the question.

Chiordi says it’s counterintuitive to think removing a significant graywater stream from onsite systems will not alter treatment in some way. “There has got to be some impact, and the impact at 40 percent reduction is going to be a lot different than at 70, 80 or 90 percent,” Chiordi says. “Homeowners are just seeing one side of the coin: ‘Let’s do this; it’s safe; it’s not going to hurt anything.’ That may not be the whole story.”

Chiordi is not a scientist or a professor. He’s just a concerned person in the industry who’s asking questions and running down as much information as he can to help people maintain costly wastewater systems as well as use less water.

Of the well-meaning people promoting graywater reuse, Chiordi says, “I’m surprised they’re going forward so aggressively without even knowing [the impact on systems]. The guys who will pay the price are the homeowners in Tucson if they don’t get the longevity in their drainfields.”

Chiordi has heard theories that downplay concern about onsite system performance when graywater is diverted. Some believe there will be little harm to systems because the mass loading of waste will be about the same, and that diverting water will simply slow the flow. But the experts Chiordi has talked to say no studies have proven this to be true or false. One of those experts is Robert L. Siegrist, professor emeritus at the Colorado School of Mines.

QUESTIONS REMAIN

Siegrist has started researching the issue but draws no firm conclusions about what this waste segregation means to onsite system performance.

“Based on the work to date, in general, diversion of mixed graywater will result in increased concentrations but equal or lower per capita mass loadings of key pollutants,’’ Siegrist writes. “Depending on the scenario being considered, graywater diversion could adversely impact the function and performance on a common onsite wastewater treatment system handling just blackwater.”

Siegrist is starting to run through various scenarios of types of graywater being diverted from residential onsite systems, both existing systems and new systems designed to treat only blackwater. He finds that while mass loadings would be lower in existing systems with graywater removed, concentrations of BOD, TSS, total N and total P would rise 1.6 to 2.2 times. And he notes that levels of pollutants remaining in graywater streams are significant enough to require effective treatment before discharge or reuse.

“With the diversion of graywater, the concentrations of consumer product chemicals could be lower in the blackwater, while pharmaceuticals and biogenic compounds could be elevated,” he concludes. “Depending on the source of the wastewater being treated, this could be considered a potentially positive or negative influence on system performance.”

HOMEOWNER EDUCATION

The lack of solid information is a cautionary tale for Dawn Long, of American Septic Service, Sierra Vista, Ariz. Long, who meticulously logs her observations about onsite system performance during inspections, has concerns that graywater reuse isn’t as cut-and-dried an issue as proponents would like to think. As she watches officials in nearby Tucson encourage graywater systems, she worries that homeowners aren’t up to the task of maintaining the systems.

A few things worry Long. For instance, if laundry water is considered graywater, what if someone is washing dirty diapers? She would consider the resulting stream blackwater. She has seen graywater systems where water is improperly ponding in the yard. She’s seen holding tanks that are not emptied in a timely manner, resulting in putrid water.

Long also suspects many homeowners use a graywater system to ease the load on a poorly performing onsite system rather than because of a concern for the environment.

“It’s going to take an educated homeowner to use it properly,” she says. “I’m not a cop. I see lots of graywater not being used correctly, but I’m not going to turn anybody in.”

Chiordi makes it clear he doesn’t want to stop the momentum of graywater reuse across the country. He sees it as a positive movement in areas with dwindling water supplies. His concern rests with making sure what is seen as a positive for the environment is in no way a negative for decentralized wastewater treatment.

START A DISCUSSION

“Arizona is proud of its record of moving forward with graywater reuse and rightfully so. We do a lot of good work here in that arena,” he says. Still, he says there are questions that onsite professionals should be asking, and he promotes an open discussion … and hopefully we can do our part at Onsite Installer.

“Anything to get the conversation going, that would be great, without impugning the efforts for graywater at all,” Chiordi says. “I think graywater is extremely important, especially in the Southwest. We’ve got to figure this out. It’s terribly important.”

Let’s start a conversation about this issue. You can share your thoughts by sending me an email at editor@onsiteinstaller.com. Or you can correspond with Chiordi at info@greentechnologiessolutions.com.