Greywater

The Old Grey Mire

by Suzy Banks

Thousands of otherwise law-abiding citizens are greywater hoodlums. You know who you are, with your washing machine draining onto your lawn or your bathtub water drenching your prized petunias. It's an irrigation source that's hard to resist, especially during droughts and water rationing, but it isn't as benign as many people suppose.

According to Jim Fulton, an engineering associate with the Austin-Travis County Health Department, there's still a chance of bacterial contamination from typical greywater sources: showers and tubs, bathroom sinks, and washing machines. Consider a household, for instance, with a new bouncing bundle of joy and all the requisite cloth diapers. Since Junior's arrival, this family's washing machine discharge has crossed through several subtle shadings from light grey to deathly black.

The majority of greywater systems - the engineered, legal kind - that Fulton and company encounter and approve are for properites west of town not serviced by city sewage. In most of the designs submitted to the county, the greywater and blackwater are split into two separate systems, each with its own septic tank and pumping chamber. Because of the $3000-4000 additional cost, these systems are usually only designed for difficult lots such as those that are small, sloping, or close to a cliff edge. Approval of a greywater system can allow less set-back from drop-offs and smaller drain fields.

This doesn't mean you can't have a safe and legal greywater system in the middle of town. In fact, legislation was passed last year to more easily allow greywater irrigation. James McCaine, with the Texas Natural Resource Conservation Commission says plumbers and the TNRCC are now in the process of writing the rules. In theory, the new regulations should allow townies more freedom to irrigate with their washing machine and bath water, provided a specially certified plumber installs the filtration tanks and subsurface irrigation lines. (With the drip lines underground, the occasional crossover of greywater to black is much less of a concern.)

The most easily understood descriptions of greywater treatment that I've found are in the book Homing Instincts by John Connell. Although the process seems simple enough, Connell warns would-be wastewater innovators to "anticipate a deeper acquaintance with your plumbing inspector and health official." Greywater irrigation systems are gaining wider acceptance, however, as water shortages become more common, especially in the West, and suitable leaching soils (i.e. the ever-disappearing top soil) become scarcer everywhere.


Resources:

The Sustainable Building Sourcebook
The City of Austin's Environmental and Conservation Services/Green Builder Program; 499-7822
An exhaustive resource, required reading for anyone wanting to build "green" in Austin, the best thirty bucks you can spend.

Homing Instincts
by John Connell (Warner Books)
This guide to "using your lifestyle to design and build your home" argues a strong case for more widespread use of greywater irrigation. It lists a couple of sources in its bibliography for more information: Residential Water Re-use by Murray Milne, Davis, CA: California Water Resources Center, 1979; and The Toilet Papers by Sim Van der Ryn, Santa Barbara, CA: Capra Press 1978.
Water Efficient Technologies: A Catalog for the Residential/Light Commercial Sector
Rocky Mountain Institute, 1739 Snowmass Creek Road, Snowmass, CO 81654-9199; (303) 927-3851
RMI has a ton of literature on energy efficiency, some of it authored by Mr. Negawatt himself, Amory Lovins. The water efficiency catalog, $25, contains the latest on urinals, washing machines and other good stuff. Ask for RMI# W91-18.