Photo credit: Penny Mayes/

Cleantech advocates often focus on the latest, most efficient way of capturing the sun’s energy, improving fuel mileage, or storing energy in batteries. These are all important. But we shouldn’t forget that small changes in something as arcane as the Plumbing Code or as low-tech as a three-way valve and PVC pipes can amount to literally tons of saved water and energy.

In 2009, California revised its plumbing code, easing regulations governing recycling residential graywater (used water from showers, sinks, and washing machines, not tainted by toilet discharge). The change allows households to install laundry-to-landscape or a shower graywater systems without a permit. These low-cost systems involve installing a three-way valve that allows users to divert their washing machine or shower graywater either into the sewer lines or to an outdoor irrigation system.

California’s Department of Housing and Community Development (HDC) is currently undergoing another revision of its graywater and rainwater harvesting Plumbing Code, in coordination with the state Building Standards Commission. Two aspects merit attention. First, the 2009 graywater change has been revised to reflect a more restrictive approach to graywater systems. Second, the rainwater harvesting section (Chapter 17) now allows for unpermitted tanks of up to 5000 gallons, up from 250, a significant improvement. Advocates are asking people to register their comments during the 45-day comment period, in order to achieve the most progressive code possible.

Again, what does all this have to do with energy?

The extraction, treatment, distribution, and use of water followed by the treatment of wastewater requires a lot of energy. A little known factoid is that a significant chunk of California’s energy bill goes to just getting water to our taps. According to California Energy Commission, about 20% of California’s electricity use is dedicated to delivering clean water from the mountains, rivers, and deltas to our faucets. In fact, the State Water Project is the largest single user of energy in California, according to the EPA. And that doesn’t include the energy it takes to heat it. With the average household using 400 gallons of water every day or 146,000 gallons/year (according to EPA estimates), water conservation and reuse is therefore also an energy and carbon footprint issue.

Graywater systems can potentially reduce domestic water consumption by up to 50%, according to the Pacific Institute. Rainwater harvesting would add to those savings significantly. The more people that adopt graywater and rainwater harvesting systems–facilitated by a progressive Plumbing Code–the more water security we attain. And this means many fewer kilowatt hours are consumed just to extract and push water over the next hill to our tap.