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10 Questions: Ralph Petroff, gray-water recycling pioneer

Water Deeply sits down with Ralph Petroff, who aims to make household gray-water recycling as common as your refrigerator.

Written by Michelle Matus Published on Read time Approx. 7 minutes

Ralph Petroff is changing the way California homes use water. As executive chairman of Nexus eWater, Petroff last week unveiled the first housing subdivision in the United States with on-site water recycling standard in every home.

At this groundbreaking neighborhood in San Diego, the soapy water from showers and sinks — known as gray water — is cleaned, treated and stored to be reused in the home.

Nexus eWater is an Australian company, headquartered in California, that brought its residential water recycling technology to the United States. Petroff spoke with Water Deeply about how gray-water recycling is changing the way Californians thinks about drought.

Water Deeply: How did this idea come about?

Ralph Petroff: About 10 years ago, I had been hired by a consortium of Australian universities, state and federal governments to advise them on technology as an entrepreneur in residence.

That was coincidentally the start of the Australian Millennium Drought, which kicked in right in the year 2000. When I got there, it was in a bad way. They had gone to the next step, even beyond what they had done in California. They had stage five water restrictions, which is not just watering twice a week, but no lawn watering of any potable water, period. So it’s a really heightened state of emergency.

As a result, the Australian government put money into things like desal (seawater desalination) but also invested in research into on-site water reuse. As it happened, I met what became the founders of Nexus at a convention fair. From day one, I thought that these guys were very sharp and they are going to really come up with something quite remarkable – and a few years later, they did.

Water Deeply: How does the technology work?

RP: This is the first robust, on-site water recycling system for the home. We take the gray water, which is about two out of every three gallons from the home. You want to take all the soaps, hair and lint out. Do this – if you do it right – you can have reusable water.

The system involves pumping heavily oxygenated water into a tank where each drop of water is circulated 40 times and it agitates. When you agitate water with a lot of detergent in it, you create an enormous amount of suds.

The soap takes out all the detergents and the detergent bonds with oil and dirt. That soapy foam is rerouted back to the sewer. Then, we put it (the gray water) through an 18-inch-thick activated carbon filter and the water, at that point, is zapped with 100 times the UV (ultraviolet light) that you would normally need. It goes through a pleated filter and then you’ve got water that goes to the storage tank.

The current version that we have uses the same energy as a normal-size refrigerator and with each generation we will probably be chopping that (energy use) in half again.

Water Deeply: What is needed to install and run this system in terms of space, cost and maintenance?

RP: It is easiest to do it during a new construction. The critical element is plumbing. You need to have the gray water separated from the black water (from sewage lines), which in a new construction might only cost an additional $500–$1,000.

If you have separate plumbing for black water and gray water, you have a recycle-ready home. Second, you put in some underground tanks, one for collecting gray water, and the other for storing the treated gray water. In our case, it is a 75-gallon collection tank and a 200-gallon reservoir for storing the treated gray water. That adds about $1,200.

All in, the cost of recycle-ready plumbing and the tanks, depending on the configuration of the house, would be somewhere between $2,000-$2,500. Then, at any point in the future, you can put in one of our treatment systems. It is plug and play; you have all the connections right there and you just plop in the NexTreater, which takes all the gray water, and runs it through the processing steps so it comes out looking and smelling like tap water. The NEXtreater is $5,200 including warranty, commissioning and installation. We would expect that a year from now those costs will be lower as volume increases.

Water Deeply: For what purposes can the treated water be used?

RP: There are eight approved uses for the treated gray water. You can use it in drip irrigation and spray irrigation, you can use it in your garden to water your fruits, your vegetables, your lawns – anywhere you want. You can also use it to flush your toilet.

Water Deeply: Can it be retrofitted to existing homes, or does it only make sense with new homes?

RP: It can be put into a fair number of retrofit homes. The easiest home to retrofit is a home that has a basement or crawl space where a plumber can go in under the house and reroute the pipes to separate the gray water from the black water.

In a new home, that might be a $2,000 operation; in a retrofit, maybe that is $3,000–$6,000 more and it is a pretty straightforward operation.

If you have a slab-on-grade, you have pipes encased in concrete and that makes it much more difficult. In some cases, it is impractical to do the whole house recycling, but if you’ve got showers on the second floor, then you can do a partial.

We think that, nationally, maybe 50 percent of the homes could do a full-house gray-water retrofit relatively inexpensively, and the other 50 percent would be either challenging or you could do a partial retrofit.

Water Deeply: Are there any current regulatory or building code barriers?

RP: We have to pass something called the NSF 350 test in order to use treated gray water in California. The test is brutal, so brutal that we are the only company that has ever passed it and that was just a few months ago. We passed it with flying colors, by a factor of 5.

Water Deeply: Where is this technology currently being used?

RP: Just last month in San Diego, California, was a kickoff to the Pacific Coast Builders’ Conference. They had a grand opening of the first subdivision in the United States with onsite water recycling, standard in every home. Solar is an option.

This is a great example of the technology moving faster than the speed of drought. We got the certification and sat down with KB Home. From the time we sat down and scribbled on the back of cocktail napkins to the time that there were actually projects in the ground with permits was less than 60 days.

We are now in discussions with a whole host of other projects and other builders across California and the Southwest. This project moved faster, but I would expect, if we have the same conversation at the end of the year, we would have a half-dozen or dozen projects underway.

Water Deeply: Why haven’t we been doing this already for years?

RP: There hasn’t been a clear, regulatory framework for deployment of solutions. By providing a clear framework, as of January 1, 2014, that gave people a set of rules.

Rules around gray water were so balkanized, with such a tremendous disparity, there was no way you could have statewide implementation, but now that there is a regulatory framework, people can do it.

Water Deeply: How has the reaction to the water crisis in California compared to Australia?

RP: Australia got into dealing with mega-droughts ten years before us. One of the things they did right was the emphasis on on-site water reuse. The thing they did wrong: they bet big on things like desalination facilities. I say they did that wrong because it took them 10 years to build those plants and by the time the plants were online, all of these other conservation measures had already kicked in. As a result, two-thirds of the desalination plants in Australia are currently in mothballs.

Water Deeply: What is the future potential, both in terms of cost and potential water savings, with recycling water? Is it like the early days of residential solar panels, which started out expensive and hard to implement?

RP: People often ask me if water is the new oil. I laugh and say no way. It isn’t even close. Water is just far more important. There are many forms of energy, you’ve got wind, you’ve got solar, there’s like eight forms of clean energy and, of course, fossil energy, but water is the world’s only un-substitutable resource. That is why it has to be put in an entirely different category.

In the energy crisis, California responded magnificently and within a couple of years, all (new) homes were solar ready, now homes have solar panels. People were saying at the time, let’s build $10 billion power generation facilities that will take 10 years to build and require massive upgrades to the grid and very sensibly, people said $10 billion in 10 years ain’t gonna solve the problem now.

And so, they went on-site.

And that is what we are trying to do: go on-site recycling with gray water as opposed to multibillion-dollar, 10-year massive plants to recycle wastewater. Recycled wastewater works, but it is very expensive and it always has a lingering odor, whereas recycled gray water is much cleaner and it has no smell.

The whole goal was to come up with recycled water that looks and smells like tap water, and that is a goal we have achieved.

I said we responded magnificently to the energy crisis; we’ve got to do the same thing with water, but do it at 10 times the pace and with 10 times the intensity while giving it 10 times the priority. We’ve got to be moving faster than the speed of drought. I think the water resources board and the governor understand that.

Top photo by Rich Pedroncelli, Associated Press

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