Designing a Water Efficient Community in Central Washington State
As for your request for new approaches to water efficiency, I’ve been designing a 10-home residential project near Yakima, Washington, where we are trying to address water issues in a responsible way. It’s still in the design phase, so some of the features may, by necessity, change based on the builder’s ability to keep costs down and ultimately be able to sell the homes for a certain price and with certain features. Check out the project website.
The site averages about eight inches of precipitation annually, about half rain, the rest snow (note this is really a high desert location!). The area has hot summers, cold winters, and a steady (drying) wind from the west, with 300 days of sun per year. The land for this home site is not arable and most of it (40+ acres out of ~52) will remain as common open space, without fences so that wildlife can roam freely.
Constructed wetlands will naturally treat graywater waste – from bathtub, shower and sinks and toilets depending on whether or not a home has the solar composting variety – using gravel and plants to filter non-toxic impurities. We are working with a company called Whole Water Systems. The constructed treatment area will cover only 2,500 sq. ft. of the site and remain “natural” with plants.
The homes are designed to accommodate solar composting toilets; bathrooms are located at two corners of the building with southern exposure, oriented so that even where homes are facing off-south, the toilet’s collectors would be sufficiently exposed to the sun to do their work. As the solar composting toilets are a sort of unknown in the market, the builder will offer them as an option. For many months, I’ve been communicating with SWSLoo on the Eloo system which appears to be the best choice for our uses. These toilets use the sun to efficiently turn waste into compostable material, are low-maintenance and have no smell; with Yakima’s 300 days of sunshine per year it totally makes sense to adopt this technology here. It may be that the first ‘spec’ house has conventional ultra-low-flush or dual-flush toilets, but a later home will be able to act as a prototype for the solar composting toilet.
We have an appropriate, simple roof for collecting rainwater. Made of standing seam metal to keep the water cleaner, it slopes to the south and north. Rainwater and snow melt will be captured in rain ‘barrels’ to be used in raised beds or on trees. The rainwater collection tanks will be stored under the deck on the north side of the homes, out of the sunlight to keep it cooler and, we hope, freer of algae development. Annual precipitation is about eight inches, but only half that is rain. Preliminary calcs, using rainfall only, show that the roof could yield about 37,000 gallons over the course of a year. However, the rain falls in large quantities, quickly, so the storage tank needs to be fairly large in comparison with the annual rainfall. We are looking at maybe 1,000 gallon storage tanks. (Editor’s note: it’s probably better to run some of the water directly to plants than to build a very large tank that is almost never full).
Low-flow fixtures will be installed inside the homes for faucets and shower heads. Plus we’ll use Energy Star-rated appliances such dishwasher, clothes washer and dryer that conserve water.
Community rules will require all-organic site and vegetation treatments. Even though there is not much water on-site, it is important to keep that water healthy and free of toxins. In Washington State, phosphates are a typical water pollutant, often from fertilizers and detergents. Landscaping will remain native except for raised-bed gardens so that no permanent irrigation system will be in place. Watering can be very targeted and specific to the raised beds, and possibly to some added fruit trees. The rest of the land uses only what falls naturally on the site.
All homes will have solar hot water. While this is not exactly a water conservation measure, plans are to educate homeowners in their new systems so that they understand the limited water resources and how their systems use the sun passively to provide domestic hot water. The solar collectors will be located prominently on the south-facing roof, that is also the entry side and visible to the community – reminders to the residents that the water in their homes is part of a renewable energy system.
Look for more information on Rocky Top Living in the next year or two!