A recent spate of road trips into drought-stricken West Texas gave me a new pet peeve: acres of clean, smooth, low-pitched metal roofs for both agricultural and oil-boom industrial use with not a gutter or rain barrel in sight. A relatively mild summer and decent rains put San Antonio in better shape, for now, but at some point we all have to grapple with one key resource: water. If self-sufficiency is part of the homesteader creed, harvesting rainwater is one of the simplest, cheapest and smartest ways to maintain your garden or landscape, reduce dependency on municipal utilities, and hone your reputation as either a good steward of our shared natural resources or a misanthropic survivalist. Water catchment is not a political stance. It’s just common sense.
We take for granted that SAWS will keep the taps flowing, but recent evidence suggests that water is, indeed, limited. The 2011 drought was the worst in 50 years and is still ravaging much of the state, proving we are not immune to water shortages. According to the Texas Water Development Board, Texas groundwater supplies are expected to fall 30 percent by 2060, with demand rising by 22 percent. Reservoirs and aquifers are dwindling statewide. Rainwater is free, easy to capture and can be stored in large quantities for a really long time.
The basic idea is to send runoff from roofs, gutters and downspouts into storage containers of some kind. If you’re using it for landscaping or gardening, it’s pretty simple. Even five-gallon buckets work, but they attract mosquitoes and fill up quickly. Most “official” storage tanks are sealed and made of materials that inhibit algae growth. There are leaf and mosquito filters if you want to get fancy. Basic rain barrels hold about 50 gallons and cost $40-$50. Larger tanks cost more, but can store hundreds of gallons. There are modular fence units, underground cisterns, large free-standing tanks in a variety of materials, even 1,000-gallon rainwater pillows that live under your deck: they fill up via downspout connections, and come equipped with a pump to extract the water.
Harvesting for household use (washers, toilets, etc.) gets a little more complicated, especially if you have a back-up system that links to municipal water supplies. You’ll need filtration and treatment systems if you plan to drink it, and an air space that keeps rainwater from backing up into SAWS territory. It’s trickier, more expensive, and best left to professionals. Still, rainwater is free, relatively clean and pH neutral and is not treated with chlorine, fluoride or other chemicals. Better for you, your appliances and your plants.
The Texas Water Development Board, SAWS and other organizations are actively promoting water catchment as part of long-term conservation efforts (see twdb.state.tx.us for guidelines, FAQs and more). Now is the perfect time to act, while the rains are with us. The standard harvest calculation is .62 gallons per inch of rainfall for every square foot of roof guttered to a storage tank. That’s 1,240 gallons for a 2,000 square foot roof.
So, back to all those acres of un-guttered metal roofs: Governor Perry’s suggestion a few years ago was that we all pray real hard for some rain. It seems to me that God might be a little irritated at the waste. Having a system in place when it does rain might be a real good idea.
Texas Water Development Board: http://www.twdb.state.tx.us/innovativewater/rainwater/index.asp
especially the archived Texas Rain Catcher Awards, which highlights residential, community, and commercial projects
Also: Very useful FAQ section
Also: The Texas Manual on Rainwater Harvesting
Texas Rainwater Catchment Association
Good article on the Lady Bird Johnson Wildflower Center website: