DIY Grey Water System for an Off-Grid Homestead

Off-Grid Water Systems for a Solar- and Wind-Powered Homestead

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By David Abazs – Being nestled in the Sawtooth Mountains along the north shore of Lake Superior has provided many opportunities, like being able to build our own DIY grey water system. It’s also presented a number of challenges for our family’s homestead. The rocky and forest-covered Canadian shield provided us with the opportunity to build our house, barn, sauna and chicken coop out of stones and timbers. The shallow soils continue to challenge our farming and have limited our wastewater options but this has also led us to develop a treatment system that we could use to irrigate our orchards and greenhouses. Being away from power lines supported our goal for off-grid electrical systems but produced additional challenges. How much power do we need, or can we use, for our off-grid water system? What happens when our power gets low? How do we get the water to our house and how do we get rid of it? Pumps or gravity? These are some of the questions someone who chooses to get their energy from the wind and sun must consider.

My occupation as a county Water Plan Coordinator has provided me the opportunity to explore regional wastewater problems as part of my job. I have researched, taught and worked with an alternative wastewater technical committee installing and evaluating alternative wastewater treatment systems throughout northern Minnesota. My wife and I have worked at making our own lives as cyclical as possible — turning all our lines into circles. In regards to wastewater, after much trial and error, I feel we have finally found a solution that works.

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Our Toilet Evolution

Most toilets require power, either pumping water to and from a toilet and septic tank, or heating and venting a composting toilet. Outhouses and non-electric composting toilets are the only toilet systems that do not need power. Because of our energy restrictions, we chose to use the SunMar NonElectric self-contained composting toilet with the addition of composting toilet with the addition of an electric vent fan. After this unit failed to perform adequately, I retrofitted it to help it meet our needs. I build a 4’ x 4’ x 4’ bin below the bathroom that could be accessed from outside the house. I cut the fiberglass bottom out of the toilet unit and installed it on top of this bin. We use the unit as it was designed, but we now dump the entire contents bimonthly into this larger bin below it. The material then has up to two years to continue composting, resulting in a product far more acceptable than what we had gotten before. Last fall we emptied the bin and put the composted material in our orchard. The vent fan consumes .07 amps at 12 volts dc, just over 20 watts per day. We runt he fan on dc, even though the rest of our house is on ac, to avoid the inverter being on 24 hours a day.

Not everyone has to go through the toilet evolution we did. There are several family-sized composing toilets commercially available that could have worked for us, probably for a bit more money than we had at the time. With all these toilets, however, an off-grid home still has to consider the power needs for successful operation. Heating elements, required by several commercial designs, do not work in a reasonably sized, off-grid electrical system. Some of these heating elements alone use more electricity than we use to run our entire farm and home. Even when a home is connected to the power grid, reducing household power consumption is a choice that will reduce the environmental damage created by most electrical power generation. Phoenix, Carousel and Clivus Multrum are all designed to be used with out heating elements. Biolet and Sun Mar NonElectric units work in seasonal or cabin situations. A less expensive option is to build your own unit. There are many designs that can work very well! I would still recommend vent fans on any composting toilet.

So What About Grey Water?

Once we were set up with our compost toilet we still had our grey water to deal with. Grey water comes from sinks, showers, baths, and the laundry but does not include toilet water. By separating the toilet from wastewater, grey water contains:

• 40% less water

• 50-90% less nitrogen

• 40-60% less phosphorus

• less bacteria and less solids

While grey water provides many advantages, it still needs to be treated. We have been working on an ecological way to not only treat, but also utilize this nutrient-rich water source safely and efficiently. Our system has been evolving over the years to a point where it now takes care of itself.

Our First Try

We first started with a purchased grey water system for home use that had a barrel, pool filter, screen filter and drip irrigation tubing. The design idea was to filter the grey water and disseminate it through little holes (emitters). In our situation we found there were many flaws. The pump was on for much too long at a time, using lots of power. The sand filter kept getting clogged and the screen filter required hand-cleaning after every load of clothes we washed. Finally, the drip tube emitters lasted an unacceptably short time. In addition, because we had installed the system in the greenhouse adjacent to our basement, we had the unpleasant side-effect of a vague, sweet (my wife called it sour), grey water smell in the house whenever the pump cycled. Not even counting the problems we had with freezing in winter, we were far from satisfied.

Deciding to start from scratch, I took all we had learned that didn’t work and created a DIY grey water system that did work. We now have a buried system that drip-irrigates 30 gallons into selected areas (zones) within five minutes with no clogging and no smell. With only two cycles a day, even though the pump is a high-energy lead, the DIY grey water system uses very little energy because of its short duration (10 minutes per day). If there is a power failure (due to lightning, for instance, in our case) the DIY grey water system is designed to overflow into a wastewater drain tile. (See design above.)

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How Does The System Work?

In a typical conserving home such as ours, grey water volume runs under 100 gallons per day. We are careful to avoid using household chemicals that can harm the system or the plants we are feeding. Our grey water travels from the kitchen and bathroom sinks, showers, baths and laundry into the septic tank.

The septic tank performs minor biological treatment but most of all serves to separate the solids along the bottom, and the soaps and scum along the top, trapped between the inlet and the outlet. The clearer water leaves the tank and enters the pod filter.

The pod filter increases water clarity while also providing a pump chamber which pressure-doses the drip irrigation system. The only moving part in the system is a high-quality sewage pump.

The soil treatment zones are where the major treatment of our wastewater takes place. Many types of plants can take advantage of the nutrients in grey water and we can send our grey water to zones in the greenhouse, orchard or yard.

Our DIY grey water system meets all the conditions necessary for a successful soil treatment system:

• The waste water never surfaces.

• Enough area is used to fully treat the water.

• The drip zones are designed to avoid freezing.

• The filter is designed to limit clogging.

Living off-the-grid we had to solve the issue of power use. With this new DIY grey water system we use less energy while providing nutrients and water to our greenhouses and orchards. This circular solution has provided our homestead with a “water resource” from a “water waste.” Now it’s on to our next challenge…solar hot water system/…refrigeration? Ahh…homesteading!

Compost Toilet Book, by David Del Porto and Carol Steinfeld, Center for Ecological Pollution Prevention, PO Box 1330, Concord, MA 01742.

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Originally published in Countryside July / August 2002

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