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Thaumas P. Ehr, Landscape Architect

Recycling and Harvesting Water for Your Home

It barely seems worth the trouble to try to collect rainwater when so little of it falls on us a year. But it turns out that just one-quarter inch of rain can fill three, 50-gallon barrels, enough to help you water your gardens and lawn, at least for a while.

In fact, at a test house in Tucson, rain supplied about 8 percent of the water used by the family that lived there, which means they used less potable drinking water to water their plants and saved a little on their water bills.

Yes indeed, it hardly ever rains. But think about how much water we waste when it does. Surely you’ve noticed waves of water splashing off of your patio and driveway during a monsoon storm and streams of it pouring off of your roof. Some estimate we lose 90 percent of our rainwater that way.

If you could channel that excess water to one spot, you could use it to water your gardens once the rain stops and your lawn dries out again.

Our sporadic rainfall might not make for a dependable supply of landscape water, but harvesting what does fall can save water and even money if you use it in evaporative coolers, your chlorinated swimming pool, surface irrigation and even for washing your car.

Here are a few things you need to know if you’d like to start recycling the water than falls from the sky for free:

Rainwater harvesting systems range from simple and inexpensive to complicated and costly. Even if you just place a big plastic trash can at the bottom of a downspout to catch water from the roof, you’ll collect enough to water your plants, at least until it evaporates. Or, you can invest in an system that will stop water from flowing off of your property and instead:

  • You’ll need to install gutters on your house. Gutters catch water before it splashes off of the roof and sends it to downspouts that can direct the flow into a barrel.
  • A designed system can not only collect the rain, it can route the free, no-salt water to specific areas of your garden or lawn for irrigation.
  • Even if your system has a filter, you should not drink the rainwater. It’s not clean enough.
  • The rain isn’t the only water you can recycle. Consider this:
  • Your swimming pool. If your pool needs draining anyway, stop adding chemicals for a few days and then siphon the water out with an electric pump (you can rent one for an above-ground pool) or the drain line (in the filter pump of an in-ground pool) connected to a hose. Let the water spray onto your lawn and gardens until the soil is saturated. You can repeat the process once the water seeps in.
  • “Grey water” from showers, bathroom sinks and washing machines. That water runs right down the drain, but you could direct it to a system that reuses it to irrigate your yard. In Arizona, you don’t need a permit to set up a grey water system as long as you follow the state’s safety guidelines, keep it on your property and recycle no more than 400 gallons a day. These systems work better on larger lots say,larger than 5,000 s.f.

A note: It’s not safe to reuse water from toilets, kitchen sinks or dishwashers, or to use grey water to water your vegetable garden or any edible plants. You could qualify for a state tax credit of up to $1,000 if you install a rainwater or grey water collection system. Check with the state Department of Revenue ( to learn if you system qualifies.

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