A lot of houses are off-the-grid where electricity is concerned, thanks to solar panels, wind turbines and battery banks. Far fewer can say the same about water.
Now there is one in Bend, Oregon, dubbed the Desert Rain House, that boasts a completely closed-loop water system. It draws no water from the municipal water system in Bend, and it delivers no sewage to the area sewage treatment plant. The house gathers all the water its occupants need from rain and snow falling on the roof, treats it to drinking-water standards on site, and discharges the drain water to a complex on-site treatment system.
Even more impressive is that the home is on the “dry side” of Oregon, so it doesn’t receive copious rainfall to fill up its on-site 30,000-gallon (110,000-litre) underground cistern. Yet it gathers more than enough water from roof runoff alone to meet all the needs of its two full-time adult occupants, who live as people do in any other home. That means its systems are applicable to a great many other locations.
The home was designed by architect Al Tozer of Tozer Design, also based in Bend. It was built to satisfy the Living Building Challenge, a sustainable development process that is more rigorous than the LEED standards for green design most people have heard about. Every component that goes into the home must be sustainably and ethically sourced. That means, for example, no PVC pipes, which are the basis of most modern plumbing systems these days.
Water Deeply recently spoke with Tozer to learn more about the house and the applicability of its systems to other sites.
Water Deeply: Is the house really entirely off-grid where water is concerned?
Al Tozer: Yes. it comes from rain and snow that lands on the roofs, it drains off the roofs into gutters and downspouts through a preliminary gravel filter at the base of the downspouts. Then it travels into filter and sterilization tanks, and is stored in an underground cistern below the two-car garage. It is then pumped into the home at a standard residential pressure.
Then the water is used and drained out of everything to either a gray water pipe or a black water pipe. Gray waters go to a constructed wetland bioreactor to be cleaned biologically, then reused for irrigation. Black water is transported via a ship’s toilet system, which is vacuum assisted, to a ground-level composting toilet –a kind of industrial-level toilet – paired with an evaporative system that pulls off as much moisture from that black water as possible to keep the conditions for composting ideal in the composting tank. Moisture either evaporates into the atmosphere, or there is landscaping irrigation.
Water Deeply: Is the house the first of its kind, in terms of the closed-loop water system?
Tozer: I don’t know of any other house like that. Is it a first in the world? I don’t know about that. And I’m guessing not. There are places in the Caribbean on islands and other places where I do know they capture all their drinking water off roofs, and they might send it to septic systems and drain fields. You might say that’s also a closed loop system because they’re not sending their sewage off site to somebody else’s system. There are many places in the world that capture water off their roofs and treat it to drink then send all that water into a drain field on their property.
But we don’t have that kind of room on an urban lot in the center of Bend. This is a very urban site, it’s right in downtown Bend. It’s as urban as Bend gets. It’s an older neighborhood and it does all of this in that limited area.
This is the only house that I know of that does the complete loop, and in addition to that is net-zero energy and is the first in the world to get full Living Building Challenge certification.
Water Deeply: And it seems like water was a major concern with the project.
Tozer: Water certainly was a concern. We live in a desert in Bend. Most people think Oregon gets buckets of rain, but not on the east side of the Cascades. It’s very dry. We live in the rain shadow of those mountains. We can reliably count on only about 9 to 10 inches a year of precipitation. So we had some concern about capturing enough water to make the whole project livable. Because it wasn’t just a main home. We also had an accessory dwelling unit, and in the end, we added another one-bedroom apartment over the mechanical room that held the composting toilet.
The water systems expert, Morgan Brown and his team – which included a biologist in the Denver area and a water systems engineer in Texas – we needed to calculate how much water we thought we would use in the home based on the appliances and fixtures that would be installed, and then pair that with Oregon state codes that allow capturing of rainwater for potable use. That was fairly intense, but all doable. It went pretty seamlessly from start to finish.
Water Deeply: But I understand the sewer side of things was more complicated.
Tozer: The sewer, on the other hand, did not go as planned. The plan was to create a constructed wetland bioreactor on site. It uses biology to purify water. Basically, it’s a hole in the ground or like a pond – not very deep and filled with gravel. And all the wastewater is directed to it. The wastewater stays below the surface of the gravel, but is in all of the interstitial spaces between the gravel. Because of all that gravel the bacteria cleaning the water have lots of surface area to attach to. It’s effectively like your own little sewage treatment plant, but there’s no smell and you can grow plants on top.
Well, the local jurisdiction had never seen anything like that and immediately refused that whole system. It was not going to happen. Over months of extended negotiations – I think it extended into almost 18 months of dialogue back and forth between the local jurisdiction, the state and the fine-tuning of all the data Morgan had to present – in the end the city of Bend did allow all the gray water in the project to go to the wetland bioreactor to be cleaned, and then to be used on site as irrigation water.
They did not allow the black water – including toilets and dishwasher drains – to go to the constructed wetland. They said you have to put all that down the sewer line. But the Living Building Challenge does not allow you to put anything in the sewer lines. Everything has to be treated on site. So it was nearly back to ground zero on the wastewater.
Water Deeply: How did you solve that?
Tozer: What ended up happening was Morgan Brown and his team – and a composting designer out of Montana and an engineering team out of Portland – put a system together using a commercial-grade composting toilet system. It’s made for cruise ships, manufactured by Jets out of Scandinavia. They also designed a one-off evaporative system that would take the moisture out of the black water and evaporate it on site.
Water Deeply: And how is it working so far?
Tozer: It has been performing in fantastic fashion since they moved in.
So far, the Desert Rain House has captured way more water than they could use. Their problem is they’ve got too much water. Part of that is due to owner behavior. They are cautious about their water use. But now they’ve thrown caution to the wind and they take baths and take showers as long as they want because they’ve got too much water.
So this opens up a lot of the country to pursuing this type of thing, including drought-stricken areas of the country, like California and Phoenix.
Water Deeply: Is there anything exotic about the appliances in terms of their water use, or is it all off-the-shelf stuff?
Tozer: It was all off the shelf, nothing revolutionary. Anybody can buy the appliances and plumbing fixtures that we used.
Water Deeply: What would you say was the cost increase for the closed-loop water system by itself?
Tozer: That would be hard for me by myself to estimate. This was a very lengthy process, and part of the process involved design time and money. But it’s significant. We’re talking more than $10,000 for sure and probably more than $30,000. In a million-dollar home, it’s a significant number, but it’s maybe a number that’s worth it compared to digging a well. In a $500,000 home, maybe it’s too much — it’s probably cost prohibitive. In a $300,000 home, no one’s going to do it, it’s not even a possibility.
Water Deeply: How applicable are these ideas to other homes?
Tozer: Well, it was expensive. But by price per square foot, this is not the most expensive home in Bend, and certainly not in San Francisco, New York or Seattle. People pay a lot more per square foot for their dwellings in many other areas.
With the water system in particular, you have to have a place to store the water. On this site, they elected to chip through solid basalt rock to carve out an underground cistern, with a concrete lining, pumps and filters. To build that cistern on site was very expensive, so the money didn’t go to fancier countertops or Italian marble. It went to a cistern. You have to have the right clients who say the closed-loop water cycle is so important, that’s what we want to spend our money on.
Water Deeply: Do you have any advice for others considering such a project?
Tozer: I would really encourage the local jurisdiction to a keep an open mind, and for the builder and designer to let those local folks know this has been done before. It was pulled off, it’s working, people are living in it, there are no problems, no environmental disasters.
I would do another one in a heartbeat. And the next time we do it, it will come at lesser cost because we’ve done it once already. And the time after that it will cost even less.
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