News Release

Posted on: January 28, 2016

MMWD Adopts Graywater Ordinance to Promote Water Conservation

The Marin Municipal Water District's Board of Directors recently adopted an ordinance requiring applicants for new water service, and applicants requesting an enlarged water service for substantial residential or commercial remodels, to install a graywater recycling system to reuse the maximum practicable amount of graywater on site.

The new requirement supports the district's ongoing efforts to reduce demand on the water supply during the current drought and beyond. The ordinance will take effect February 1, 2016.

Graywater includes wastewater from bathtubs, showers, bathroom sinks, and clothes washers. Instead of sending this water down the drain, graywater systems divert water from these sources for reuse on site, most commonly for landscape irrigation.

"Even when full, our reservoirs hold only about a two-year supply of water. So it's important to make the most of our water, and that includes using it more than once when possible," said MMWD Conservation Manager Daniel Carney. "This ordinance is an important step toward maximizing use of graywater, when practical, to help preserve our precious water resources."

In addition to saving water, graywater reuse can provide other benefits for customers including a reliable source of irrigation water during drought and greater awareness of water use. Keeping graywater on site also lessens the burden on local sewer systems.

MMWD's ordinance is targeted to new construction and remodels because installation of graywater plumbing and irrigation systems is most cost effective at these times. The additional costs to connect drain lines from showers, bathroom sinks, and laundry facilities is relatively small compared to overall construction costs.

MMWD does not issue permits for graywater systems, but does encourage their use whenever possible. Graywater systems are governed by California Plumbing Code as well as Marin County and local jurisdictional codes. Under state code, graywater does not include wastewater from kitchen sinks or dishwashers, or water contaminated by any toilet discharge.

In addition to the new ordinance, MMWD is promoting graywater reuse for all customers via rebates up to $50 for laundry-to-landscape graywater systems. Basic laundry-to-landscape systems typically don’t require permits and require minimal alteration to existing plumbing, making them one of the simplest, least expensive ways to “go gray.” Visit for details.

Media Contact: Ann Vallee
Phone: 415-945-1196

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