August 30, 2008

How to Do More with Water

[Published in AIA East Bay's ARCHnews September 2008]

Producing drinking water is extremely energy-intensive. ASHRAE reports that energy costs make up 80% of the typical water bill. Efficiency is a first step, but we really need to use locally produced, non-potable water to be sustainable. Our chief uses for non-potable water are toilet flushing and irrigation.

The real excitement comes from integrating architecture into the water cycle. With architecture we “harvest” two sources of non-potable water: rainwater and graywater.

Architectural expression of rainwater collection and storage. Buildings already collect rainwater in leaders and downspouts. Making water part of schematic design leads to rooflines that take on a receptive posture and concrete tanks that serve as basketball courts.

That brings us to graywater. Graywater is bathwater (plus bath sinks and showers). The English spell it greywater. The most harmful things in graywater seem to be detergents and cleansers, but graywater also contains bacteria from our skin. Avoid storing graywater unless it’s treated in an appliance like the BRAC, Pontos Aquacycle, or Aqus. These units filter, chlorinate, and store the water for toilet-flushing. San Francisco and Mendocino County are taking the lead in permitting these appliances in California.

Reconnect architecture with horticulture. A better use for graywater may be irrigation. Laura Allen of the East Bay’s own Graywater Guerillas explained that organic particulates in graywater are good for soil health, turning a waste product into a resource. When our grandparents “threw out the bathwater,” they threw it onto the vegetable garden. We are seeing a resurgence of residential horticulture, using mulch basin technology to distribute the graywater with no storage. The gardens of the Sunset Idea House in San Francisco are irrigated with a system designed by the East Bay firm WaterSprout.

Regulations. Appendix G in the California Plumbing Code (written by sewage disposal engineers, not horticulturalists) regulates graywater. Designing a permittable graywater leachfield makes building your own moonshine distillery seem cheap and easy. The absence of realistic code guidance at the scale of single-family homes has led to elegant R&D by rogue horticulturalists, explained in excellent detail on the web. The Arizona and New Mexico graywater codes allow these clever systems, and we need to pressure our East Bay jurisdictions to emulate them.

Low tech:
East Bay’s Greywater Guerillas. Laura Allen, co-editor of Dam Nation: Dispatches from the Water Underground.
Texas Manual on Rainwater Harvesting, online, now in its 3rd Edition.
Arizona Graywater General Permit provides guidelines and requires no review or inspection.

High tech:
High Performing Buildings magazine, Summer 2008 issue on rainwater, subscription free to architects,
Pontos Aquacycle (by Hans Grohe),
Aqus (by,


Anonymous said...

Very enlightening and beneficial to someone whose been out of the circuit for a long time.

- Kris

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