Well it’s always a little nerve-wracking when finally cutting the ribbon on a new project, no matter how much you’ve tested it. Even though I dropped a few 15 gallon buckets of water down the chute from the Sugar Shack’s rooftop to test the rainwater catchment system after I finished the build, and even though I added an extra bead of silicone caulk to those pesky corner-rounding spots in the rain gutters, there was still that nagging sense of… what if?
No more. We got our first storm in the neighborhood yesterday, a few solid hours of rain in the afternoon, and I couldn’t wait until the sun popped out to find out how the system was doing. The inflows were dropping a heavy flow into the barrels and doing just fine. After the rains had passed our four barrels were about half full, about 110 gallons caught.
Now I can get a more accurate idea of how much water we can catch: I went to www.noaa.gov and typed in our zip code. The nearest weather station to us is on the USC campus, which is a few miles away, but it’s close enough to give an idea of how much rain we got. The USC station got about 0.16 inches of rain during the storm; an average LA rain year of 15 inches would fill our barrels almost 50 times, though most of that will occur over the course of an entire six month “wet” season, and anything over 0.3 inches at once will be lost to the overflow.
It’s a good thing then that I actually improved the garden drainage by shunting the overflow directly into the drainage pipe, and there’s ample opportunity (and barrels around the garden) to do a rooftop catchment as well.
Here are some shots of the gravity-fed rainwater catchment system I just finished for the Sugar Shack, the 14-person urban intentional community in the heart of Mid-City LA where I have been residing the last few months. It has been an incredible learning and growing experience, one that has begun to fulfill my vision of “permaculture structures” that are amazingly beautiful and amazingly multi-functional, and I hope this system will serve the community for decades to come.
This is a 220-gallon system composed of the four 55-gallon drums you see in the photos, all acquired by one of our housemates from a TV shoot he worked on a couple of months ago. The system has two collection sources, on the left a roughly 80 square foot sloped second-story roof area, and on the right the roof deck over the community room. On that side I think we’ll get about 200 square feet of collection area, based on how the roof up there slopes.
In an average LA rain-year, with about 15 inches of rain and about 85% efficiency in the system (we’ll lose a bit of water to some gutter leaks even as I’ve improved them extensively), we can potentially catch up to 2,200 gallons, assuming we cycle the water into the garden between the usual run of winter and spring storms.
For every foot you raise the rain barrels, you get about one pound per square inch (PSI) of pressure, so I built the table to raise the barrels about 2-1/2 feet off the ground and stabilized it with concrete pier footings on a bed of sand. When the barrels are full, the added height will yield a pressure of about 5 or 6 PSI, enough to run a hose around the garden (and maybe better than our showers, I might add :)). Plus a double coat of eco-friendly Penofin oil finish on reclaimed wood otherwise headed for the garbage is amazingly beautiful, waterproof, easily restored, and will last for years.
Learning about rain catchment in the last couple of years, I was compelled to take the project on as a gift to the community; like any well-designed permaculture system, a good rainwater catchment system as part of a larger ecological strategy can provide multiple “yields” or benefits to residents and communities. Some of these are hidden until you look a little closer at a good system and what it can do. Catching water for garden use is actually just the beginning, and more than it seems to be at first glance. A well-functioning system
- Keeps local moisture local. Instead of shunting rainwater uselessly and often toxically down storm drains, captured rainwater cycles through your garden, then percolates through the soil and back down to the local aquifer or evaporates from the leaves of plants. Either way the water gets naturally cleaned in the process and eventually becomes available to plants, animals and people in the watershed to use again either via rain or wells. Even just putting filters made of old window-screen on the inflow points of your system can cleanse the inflow more thoroughly than many municipalities now do, even if some of that inflow just ends up in storm drains as excess.
- Converts dollars into ecosystems – the system costs some money to build, but then increases your self reliance as opposed to dollar reliance. You spend a little money only once, rather than continuously for costly municipal water unsustainably imported from somewhere else, and the captured water supports your food forest.
- Can save lives in a disaster. In LA, like much of the world, fires are a fact of life and when the municipal water supply is taxed, 220 gallons to wet the ground can mean the house is still standing. Even non-potable water can be boiled and drank in an emergency as well; 220 gallons for the Sugar Shack can mean a 6-day emergency supply for the house’s 14 residents.
- Can take the pressure off aging infrastructure. In the US, much of our water infrastructure is approaching the limits of its design-life. Considering the condition of our institutions and economic system here in the US, we can’t count on these systems getting redesigned or even restored to original functionality any time soon. “We the people” must now shoulder the burden of building a decentralized infrastructure, but this can be an opportunity.
- Can include structural elements that can become trellising for vertical gardens. The truss beams on our table will make nice supports for tomato vines.
- Can act as thermal mass, dampening temperature fluctuations around the garden and even part of the house.
- And can give you more water than you might expect. Depending on your location, you can perhaps expect to see your system fill several times during a season. The system I built here in Los Angeles for instance is a 220 gallon system; during an average winter, I expect that it will get filled three or four times based on the square footage. To see how much water you can collect from a system, click here.
In the near term, I’ll be posting some video on Youtube showcasing the Sugar Shack system and releasing a short e-book on how to build your own rainwater catchment system. For now, enjoy the photos while your party is reached and stay tuned.
Oh, and let it rain, let it rain, let it rain!