Using a Rain Barrel

A rain barrel is a device that collects and stores rainwater that would normally flow off of your roof for later use watering your flower or vegetable garden or your lawn. The amount of water you can collect in these barrels from just one relatively small precipitation event is quite impressive. A 50 gallon barrel can fill up in minutes from a rain of only half an inch and that water can then be saved to use during dry periods or it can be fixed to slowly release the collected water to your plants over an extended period of time.

Why consider a rain barrel?

The use of rain barrels can save you literally thousands of gallons of water during the summer when, typically, less rain falls and the price of municipal water goes up. Rainwater is also a naturally soft water meaning that it lacks the minerals and/or chemicals typically associated with groundwater or water from municipal water systems. It is relatively clean (depending on where you live), uncontaminated and full of nitrogen from the atmosphere so your soil, and thus your plants, will love you for the rainwater. Rain barrels also reduce storm water runoff to your local watershed thus keeping pollutants like oil, bacteria, street toxins and sediments out of natural systems. Finally, rain barrels are dirt cheap. While you can make your own rain barrel, a ready-made 50-60 gallon rain barrels with a screened cover, overflow and outlet hose run from about $85-$135 and they are worth every penny.

Be sure to check out the Rain Barrel Guide for great advice, tips and answers to your more detailed questions.

There are several considerations to keep in mind when installing a rain barrel. First of all, the water you will collect is coming from your roof and some roofing materials can contaminate your water. If you have asbestos shingles, tar or gravel shingles, aluminum paints or lead soldered gutters and downspouts you’ll want to think very careful about how you use the water you collect and you will NOT use it on edible plants (see the Rainwater Harvesting section of this website for more information).

Next, get an approximate idea about how much water you use to decide how much you want to collect. This will inform what your system will look like and what you purchase. As the Rain Barrel Guide points out, most utility bills measure water use in cubic feet of water and 100 cubic feet of water is equivalent to 748 gallons. So, if you have used a total of 110 CCF for the year, you can multiply 110 x 748 to determine the number of gallons (110 CCF x 748 = 82,280 gallons).

Regardless of how many barrels you buy, be sure your barrel is made of a food-grade plastic that incorporates a UV protection. You’ll want to make sure that you have a tight-fitting screen lid to filter particles when the water comes in and to keep animals out.

You’ll want to take mosquitoes into account, too. Make sure your screen is small enough to keep them from getting in and releasing their larvae. One method I’ve seen is to have a screen with larger holes on top with a pair of trimmed pantyhose attached to the…um…underside. The larger screen will keep large contaminants out while protecting your smaller mosquito screening pantyhose below. Another method? Goldfish. Yes, small goldfish love to eat mosquito larvae. With enough air, a few goldfish in each barrel will keep your rainwater clear of mosquitoes and will excrete a nice fertilizer for use in your soil. Whatever you do, I strongly DIS-courage chemical insecticides.

Another consideration is algael growth. I do not consider algae to be much of a problem. It’s great fertilizer. That said, too much of a good thing…. Algae can clog your spigots and valves but the solutions out there (bleach, anti-fungal chemicals) often cause more trouble than they are worth. If you are afraid that you may have too much algae, use a dark colored barrel and find a lit that keeps sunlight out. Also, I recommend a good cleaning of your barrel after the growing season ends and don’t let the water sit over the winter.

You’ll also want to make sure that your rain barrel has an automatic overflow hose that will move any extra water downhill and away from your home in large rain events or very wet years. This will help protect your foundation from damage and your basement from flooding. During the winter you might want to consider moving or covering your rain barrel so that it doesn’t fill and crack when frozen. When you do this, be sure your roof downspout is properly positioned so that melt water doesn’t pool near your foundation. Finally, keep an eye on your barrel. As with all pieces of equipment you’ll want to keep it in proper function condition by checking for leaks, clogs and other minor issues.

Once you get your basic system in place there is always room to tinker and get fancy. You can put water filtration systems on your systems or use specially-made UV lights that kill bacteria and small pumps can be hooked up to make distribution easier. For a good sampling of diverter kits, pumps, linking kits and just plain barrels visit Clean Air Gardening.

Now that you’re all set, simply hook your barrel up to a hose or to your drip system and pray for rain!

Here’s a great resource on safe use of rain barrel water in the vegetable garden.


Jim O’Donnell gardens in the mountains of northern New Mexico. A certified permaculture designer and ecological restoration specialist, Jim’s first book Notes for the Aurora Society was published in 2009.

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