Sustainable Living: Catching rain for the summer drought

This was an unusual summer in San Lorenzo Valley, with respect to weather, especially if you consider how few tomatoes ripened in people’s backyards. Usually it’s hot and dry — drought conditions, to be exact.
That explains why at least half of all water consumption in California is used for landscaping and gardens. Gardens in particular require between 2 and 5 gallons of water per square foot per month, but most of us use way more than that because of inefficiencies (excess water the plants can’t use or which is evaporated into the air). The average U.S. household uses about 400 total gallons of water per day.
Someone with a 100-square-foot garden who is fairly efficient — let’s say 5 gallons per square foot per month — will have to irrigate with roughly 2,500 gallons of water over the five or so months when the rain doesn’t fall. If you live in the sand hills, as I do, plan on losing even more water to fast-draining soil.
So it makes sense to catch and save some of the rainwater that falls throughout the winter for use in the summer. Rain catchment systems have become more and more popular in California and throughout the country, but it helps to start out with an honest assessment of what is needed.
Many of the catchment systems on the market, as well as the do-it-yourself plans that can be found online, employ a 55-gallon, food-grade plastic barrel. Considering the scenario above (500 gallons of water per month), that barrel of collected rainwater would be empty after about three days in a typical summer.
Sure, that’s 55 gallons of water used more sustainably by taking it directly from the source. But it really is just a drop in the bucket.
I had originally planned to do a four-barrel system, one on each corner of the house, but some quick math told me it was probably better to invest in a much more serious water storage system. So I gave away the 55-gallon barrels I’d collected. (I still have two more I’m willing to give away.)
One of the takers was building a water catchment system for her hens, and the size of the barrel probably was enough to cover a substantial amount of their water needs. But humans, especially considering our outdoor use, require far more.
In places where rain falls throughout the year, like my home state of Missouri, it probably makes more sense to use smaller tanks, because they get refreshed throughout the heavy-usage months. But in California, and more specifically in Santa Cruz County, a water catchment system should account for the two dominant seasons.
It’s also crucial to employ the most efficient water-use policies in your home and property, especially drip irrigation and drought-hardy landscaping.
Fortunately, we have some great resources for large-scale water catchment systems in the area. The first place that comes to mind is Mountain Feed & Farm Supply in Ben Lomond, which sells large storage tanks that hold thousands of gallons of water. They’re not cheap, but they certainly account for the reality of water use during the summer months.
Just how much water you can reasonably collect from your roof depends on a number of factors. But, generally, 1 inch of rain on a 1,000-square-foot roof will yield 623 gallons of water. Santa Cruz County receives more than 30 inches of rain each year (and the San Lorenzo Valley from 40 to 50 inches), so a 1,000-square-foot roof conceivably could catch about 20,000 gallons annually.
I’m still trying to plan an effective catchment system for my home, so I’d be curious to hear what others in the area have done.
Steve Tanner is a writer and journalist living in Ben Lomond with his wife, young daughter, dog and four hens. He is on the steering committee for Transition San Lorenzo Valley, a local nonprofit committed to creating a more sustainable and resilient community. For information: www.transitionslv.org.