Rainwater for Indoor Non-potable Use
Yay! We got the permit for our rainwater harvesting system for indoor non-potable use. Up until now we’ve focused our attention on thermal comfort and energy consumption in our home. Now we shift our attention to water — the precious natural resource we can’t live without. In this post I’ll share the background of how we got here on our green journey and why it’s important.
Most of you know that California is in the middle of a drought right now. When I read this article in New York Times I was reminded that residents of Santa Cruz have been practicing water conservation for a long time, ever since the drought in the 1980’s. The effect of the conservation effort is reflected in the current volume supplied by the local water district: 30% less today than it was in 1987. Unlike San Francisco and nearby cities in the Bay Area, Santa Cruz is not connected to the California Aqueduct and we don’t have water piped in from remote sources. Our drinking water comes from local sources and residents here are not a fan of desalinization so we make do with less water per person. On May 1, 2014, new rationing allotments and progressive surcharges went into effect. For single family homes this means 249 gallons per day (assuming 4 people living in the house) or 62 gallons per person per day. For the 2 residents of Midori Haus the allotment comes out to 124 gallons per day.
Currently we are using well below the allotment amount. Let me show you our recent water bill. By the way, I used to simply file away the water bill after I paid it and haven’t paid much attention to the data. The current drought condition got me curious about typical usage volume and for what purpose. If you’re also curious have a look at the middle portion of this page on Sierra Club’s website that shows the breakdown of household water use. I’m sharing my utility bill here with you as food for thought. I invite you to pull out or download your water bill and simply notice how much water your household uses.
Last month (May 2014) we used an average of 52 gallons per day (only 43% of our allotment) and our annual average water consumption was 82 gallons per day (66% of our allotment). I’m pretty happy with our our low water usage. And we’re not super frugal about our behavior. We do about 8 loads of laundry per week, run the dishwasher almost daily, prepare 2-3 meals at home daily, and I’ll even confess that I’ve never outgrown the teenage syndrome of long showers. The main reason why we have low water usage is because we don’t have a lawn and most of our trees have tapped into the water table under the soil so we don’t water them. It also helps that we have super efficient water appliances and fixtures in the house.
In a separate post I’ll show you the different components of water saving features we have in the house today. For now let me explain what we mean by non-potable use of rainwater catchment system.
Non-potable means not suitable for drinking. So what are the uses of non-potable water inside the house? Toilet flushing and laundry. At this point I invite you to pause and think about the water used to flush the toilet. Water is extracted from the ground, river, or reservoir then treated to make it safe for drinking at the water treatment plant. Then the clean drinking water is pumped through the network of pipes from the water treatment plant to your home. When you press the button or the handle on your toilet to flush the pee or poo you are using clean drinking water to transport them to the sewage treatment plant or into your septic tank. Hmm. Seems like a lot of energy and resources are expended to flush the toilet. So, what if you collected a portion of the rainwater falling on your property and used that instead to flush the toilet? That’s what we’ll being doing.
The notion of using rainwater to flush toilets and doing laundry is no longer exotic. The indoor non potable uses of rainwater is spelled out in the California Plumbing Code now. Chapter 17 of the 2013 California Plumbing Code describe the requirements for non-potable rainwater catchment system. Note that even if it is part of the plumbing code the building officials doing the plan check may not be as familiar with this yet so they may grace you with extra scrutiny. For us it wasn’t an over-the-counter permit and it cost us over $900 for the permit. Let’s hope that the permit process will be faster and cheaper as it becomes mainstream.
How did we get the inspiration to do this? About 3 years ago we visited the dormitory at the Green Gulch Farm at the San Francisco Zen Center for a Passive House Tour. It was there where we first saw the installation of rainwater harvesting system to flush toilets and to do laundry. We’ve been wanting to do this at Midori Haus but the details of the permitting process wasn’t clear when we were in our home remodel construction phase. So had some pre-plumbing put in place and we decided to shift the implementation of the rainwater system to a later phase. (Remember, this was before the 2013 California Plumbing Code update). When we learned about a local program to evaluate the water quality and cost effectiveness of non-potable rainwater harvesting system for indoor use we jumped on it. We filed our application with Ecology Action, a local environmental nonprofit organization, back in October 2013. In January 2014 we were delighted to hear that we’ve been selected as one of the 7 participants of the study. The rebate and technical assistance of this program is funded through the Proposition 84 Monterey Bay Regional LID Planning and Incentives Program grant. Sherry Lee Bryan of Ecology Action has been instrumental in providing technical assistance. Thanks Sherry!
Some of you may say, “Why worry about the small reduction in household water use when the largest consumer of water is electric utilities and agriculture?” Well, if you’re looking at the aggregate data for the country and if you are in a position to do something about it then by all means please focus your efforts in those areas. I am not in such position and as a homeowner living in an area where we rely on local watershed for our drinking water I’m doing my part to save water.
Curiosity tidbit: Water is the 2nd largest chunk of spending by our city government (Santa Cruz).
Next month Jon Ramsey and his crew from AquaSoleil will be installing a green 4,995 gallon tank in the corner of our yard along with the agricultural grade pump. They’ll make the necessary connections to the plumbing and the system will be tested. Then we wait for the rain. It won’t be until we get a good storm or two to fill the tank to see this system in action. This could be as early as September (wishful thinking) or as late as November (more likely the case).
I will share the photos and notes of the system after it’s installed in July.
About the Author
Chie is one of the co-creator of Midori Haus. When she is not sharing her stories of transforming an old house and giving tours, she enjoys trail running and hiking.