While the average American homeowner uses about 69 gallons of water per day for everything from taking showers to flushing toilets to washing laundry, Billy Kniffen and his wife use just 18 gallons each. The Menard, Texas, homeowners have a good incentive for keeping careful tabs on their water usage: They rely 100 percent on collected rainwater to supply all their indoor and outdoor water needs.
When the Kniffens moved to a property just outside the Menard city limits, they didn’t have much of a choice. “There was no other source of water,” says Kniffen, an extension agent with Texas A&M University. “There was no suitable groundwater for a well, and since we were outside the city limits we couldn’t tag onto the municipal water supply.” So they installed five 3,000-gallon polyethylene tanks and another 1,500-gallon tank to collect the rainwater that funnels off the roofs of their home and barn during storms. (The area averages around 25 inches of rain a year.)
Now, when one of the Kniffens turns on a tap inside the home, a pump moves the rainwater through a series of filters back to the house. Not only do they skip the water bill, but they’re completely satisfied with their water quality.
“I’ve gotten to where I don’t like the smell or taste of any other water,” Kniffen says. “And because we experience less mineral buildup, we’re expecting that all of our appliances should last a lot longer.”
Who Should Harvest?
Even as population increases and climate change make it clear that our limited supplies of fresh water won’t last forever – and as more municipalities consider raising the price of water as a result – rainwater harvesting is still something of an anomaly. Why? “Because you turn on the tap and water comes out,” says Doug Pushard, the Santa Fe, N.M-based owner of HarvestH2o.com, a website devoted to rainwater harvesting. “In the city, water has always been available, so it’s easy and cheap.”
But collecting precipitation can be a simple, eco-friendly way for homeowners to supplement their existing water source. “All domestic water is rainwater,” points out Stephen Colley, an architect in San Antonio. “A rainwater harvesting system just short-circuits the route between raindrop and drinking glass.”
Even if you’re not an eco-warrior, there are good reasons why you should consider collecting rainwater. In the Texas hill country near San Antonio rainwater harvesting systems are popular when wells are too expensive to drill, or when the quality of groundwater isn’t clear. “If you have a well system, you’re always at the mercy of the condition of the septic tanks upstream,” Colley says. “You have much more control over cleaning rainwater.”
Others collect rainwater for keeping landscapes alive in dry climates, where 30 to 40 percent of total water demand heads outdoors. Santa Fe resident Amy Bunting began catching rainwater when even her drought-tolerant Austrian pines were flagging without supplemental water. Although she relies on municipal tap water inside her solar house, she’s installed several cisterns next to her home, with a total capacity of about 1,600 gallons of water, to feed into a drip system for her native plants.
Even when her area gets a good dose of winter snows or spring rains, Bunting reminds herself that drought is an omnipresent threat. “There’s a Spanish saying: Agua es la vida – water is life. We need to be aware of that.” And by collecting rainwater, even just for outdoor use, she’s become far more conscious about reducing water waste inside her home.
System Basics
Whether you plan to collect rain for drinking, flushing toilets or helping your garden grow, you’ll need five basic elements to make your system work:
A catchment area. A good rule of thumb is that an inch of rain landing on 1 square foot of rooftop produces a little more than half a gallon of water. (An expert can give you a more precise idea of how much water to expect; see sidebar.) Not enough water? You can expand the surface area you have for collecting rainwater by catching rain from the roofs of barns or outbuildings, or even installing a simple pole barn for that purpose.
Avoid materials like copper and asphalt, which can leach chemicals into the rainwater you collect. If that’s the kind of roof you have, you may be able to apply a potable-quality roof coating to avoid problems.
A means of conveyance. Existing gutters and downspouts are usually sufficient, though if your area is prone to downpours, an extra-large gutter will help prevent overflow. (A 12-inch gutter does the trick in Texas.) You’ll also need some pipes to funnel water into your storage system. Locating your storage tanks as close to the catchment area as possible will reduce the amount of piping you’ll need.
A storage system. Rainwater can be stored in anything from a high-quality plastic trashcan to an interconnected system of underground polyethylene cisterns. The size and placement of your tanks depend on a number of factors: how you’ll be using your water, how much you estimate you’ll need, how much rain your area typically gets and so on. The more rain your area gets throughout the year, the less storage space you’ll need, because you can count on fresh rainwater to frequently replenish your supply.
“I sent a 900-gallon tank to a man in Ketchikan, Alaska,” says Pope. “It rains 200 inches a year there, so that will be plenty. But if you’re in Arizona, you need to store as much water as you can.”
Just as the type of storage system you use can vary widely, so does pricing. At http://www.rain-barrel.net, a basic 55-gallon tank with a spigot and connection hose runs $125. At http://www.watertanks.com, a 1,700-gallon polyethylene underground water cistern costs around $1,600. Visit http://www.harvesth2o.com/vendors.shtml for a list of vendors around the country.
A filter. If you’re using a rain barrel for landscape watering, your filtering system may be nothing more than a mesh lid and a Mosquito Dunk, a donut-shaped tablet that releases Bti, natural bacteria that kills mosquito larvae.
If the rainwater you collect is headed into your house, you’ll need a more sophisticated filtering system to kill bacteria and clean out dirt, dust and debris. Multiple layers of charcoal, sand, limestone and gravel filters are common, as are ultraviolet light filters that eliminate potentially harmful microbes from drinking water.
Many rainwater harvesting experts recommend a roof washer, a device that diverts the first five to 100 gallons of rainfall – and, presumably, most of the dust and bird droppings that wash up with it – away from your storage tanks. But simply cleaning gutters regularly helps prevent water contamination.
A distribution system. When you’re storing water in rain barrels to keep nearby plants green, a spigot, hose and the force of gravity may be all you need. More complex systems usually require an electric pump to move water from the cistern, through the filters and to the intended point of use.
Just Do It
According to Pope, an average indoor-use system for two people can cost around $12,000. But don’t let the price tag intimidate you. Just start small.
“It’s easy to get started with a rain barrel from Home Depot or a garden supply store,” says Pushard. “Once homeowners actually have the rain barrel and see how easy it is, they’ll get another or upgrade their system. It’s really getting them to take that first step.”
For Texas homeowner Billy Kniffen, there’s no going back. “We’re proud that we’re on rainwater,” he says. “We feel like we’re doing good, and we wouldn’t want to change that even if we could.”