How to Harvest Rainwater for Your Garden

March 24, 2011 One comment View all articles in Lawn and Garden

The saying goes, “you don't know the value of water until the well is running dry.” With more and more attention being called to the increasing water crisis, it's getting harder to maintain the belief that water is an infinite and exploitable resource.

It's important to conserve when watering, but many of us have been ignoring a natural, renewable resource that can make our gardens more eco-friendly and cut costs from our municipal water bills: rainwater.


Ten inches of rain falling on an average roof (1,360-square feet) during the spring and summer yields 8,160 gallons of rainwater. Assuming you have the roof part covered, here's what else you'll need to begin harvesting gallons and gallons of rainwater for landscape irrigation and other nonpotable uses:

  1. Gutters and a Downspout: High quality gutters can be expensive, so if you don't already have them on your house, this investment is the biggest cost you'll face. Just installing rain gutters on the east-facing side of your house will keep your rain barrel full all summer long.
  2. A Downspout Diverter: To make filling up your rain barrel more convenient, fit your downspout with a diverter. They come with several feet of leader hose and some brands even have an automatic overflow control that directs water back to the downspout when the barrel is full. They're usually around $30 and can be found online at or at your local Home Depot.
  3. A Storage Tank: Rainwater cisterns are usually made of either plastic or concrete and can hold hundreds or even thousands of gallons of water. A wooden or plastic rain barrel from a hardware/ garden supply store typically holds 40 to 80 gallons of water and will usually cost between $74 and $150. These are great if you want to start small and keep things simple; and if you have the space several barrels can be set up in tandem. Take a look at our Do It Yourself Rain Barrel article which shows how you can re-purpose a used barrel or trash can and save yourself money over buying a new rain barrel.
  4. A Debris Screen and a Lid: Before the water goes into your tank or rain barrel, you'll need a debris screen to filter out leaves and pine needles. If the debris isn't filtered, it will collect at the bottom of the tank and may clog the outflow. Screening your rain barrel also prevents mosquitoes from breeding in the water. If the rain barrel you buy doesn't already come with a removable, purpose-made screen, you can easily make one from nylon window mesh. A mesh filter or screen, in addition to a well-fitting lid, will also keep children and pets from falling into the rain barrel.
  5. A Distribution Device: Plants love rainwater because it's naturally soft and free of chemicals and dissolved minerals. Using rainwater on your lawn and garden can also reduce salt accumulation in the soil, which can be harmful to root growth. To use all the rainwater you've harvested, you'll need either a standard spigot or a short length of hose that's installed near the bottom of the barrel and has an on/off valve. You can attach a longer hose to reach your garden or just use the spigot to fill up watering cans.


Nancy on March 26, 2011 at 12:43 a.m.

I just clipped off my aluminum downspout to the right length and sit it in a strainer lined with filter fabric set into a hole in a used cider barrel found at a garden market store. It also needs a spigot at bottom and an over flow hole near top. Don't forget to turn over and drain before the Winter freeze.

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