Harvesting Rainwater with Rain Barrels

Make plants happy with rain water

Water may be mundane, but it's not cheap. Necessary for sustaining every activity on our planet, it's worth respecting. In the US, the amount of water used per person typically ranges from between 70 and 100 gallons a day for everything from washing clothes to watering the lawn.

There are two aspects of water usage for homeowners to consider. One is conserving water and using what they have efficiently and the second is to consciously work to reduce the amount of water that flows into the municipal water system.

Conserving water

A few tricks to reduce water usage are well known:

Rainwater collection using low tech rain barrels

In addition to rethinking water usage, it might be time to consider employing that old-fashioned solution—the rain barrel.

c. 1910

See, see my playmate,
come out and play with me
and bring your dollies three.

Climb up my apple tree
Holler down my rain barrel,
Slide down my cellar door
And we'll be jolly friends, forevermore.

Once upon a time, not that long ago when people still raised their own chickens and canned vegetables, many houses sported rain barrels or a tank of some sort. Used for watering the garden and the chickens, homeowners understood the value in capturing and using rain water. Many women found mineral-free, soft rain water to be ideal for washing and rinsing their hair.

Without any but the most minimal filtering, run off from your house and garage can supply a decent amount of water for plants. During a single day of rain, the volume of water can range between 300 to more than 700 gallons of water. If your home is connected to the local sewer system, run off picks up contaminants and flows directly into the storm water system. In metropolitan areas, storm water treatment is a huge and growing problem. Simply disconnecting your downspouts from the system and directing the water flow away from the house using splash blocks designed for that purpose is recommended by many cities.

Complex rainwater harvesting systems are in their infancy and many systems are simply not cost effective. Underground cisterns, which have been used for centuries, are expensive to put in and the return on investment could take decades to realize. Even if you build one, if you live in or near a city, local codes may require that ALL water in a house be potable. That may require filtration and treatment to bring your water harvest up to code as far as the plumbing inspector is concerned. If you live outside a city, you probably have more room for innovation. Keeping a rainwater harvesting system simple allows for creative solutions without going broke in the process.

For the typical homeowner, a rain barrel stationed at each downspout can yield a decent amount of water for auxiliary irrigation, be simple to set up, and reasonably cost effective.

How much rain?

How much storage capacity you need to take advantage of all that free water depends on how much it rains where you live. The calculation is

_____sq. ft. of building footprint x 0.6 = ______ x 0.8 (efficiency factor) = _______ x n (where n is the number of inches of rainfall per year) = _____ gallons per year

Please feel free to use our rain barrel calculator.

Obviously, you won't need to store all of it at once, but in the interests of efficient water capture, you'll need to plan for anticipated rainfall by month. Some months will be wet and others will be dry as a bone. The point is to use captured water as much as possible during the dry months. The benefit to you is lower water bills during the dry season, as well as keeping excess water out of the storm system. By daisy-chaining a couple rain barrels together at each downspout, you could capture enough water to get through the summer with a significantly lower water bill.

A Portland, Oregon homeowner with a 1500 sq. ft. single-story home could expect to capture about 25,000 gallons a year—or 480 gallons a week. With six downspouts, you might need as many as two 55-gallon containers per downspout.

Surrounding your house with rain barrels is probably not an aesthetic solution, but you can still capture enough water to reduce impact on the storm system.

Setting up your rain barrel

You can purchase a ready-made rain barrel from one of a variety of sources, which has a removable lid, a screen to trap debris that comes down the spout, and a tap where you can attach your hose. Check local hardware stores and garden centers or order them online. Purchased this way, they are easy to roll up to the downspout and connect. The downside is the cost: each rain barrel could run you between $80–150. If you have four downspouts you can quickly run into some serious money.

Do it yourself

For the handier homeowner, constructing your own from found materials is certainly easy enough to do, though more labor intensive.

  1. Find a source of large 50–80 gallon food quality plastic containers. (A Google search for "food grade barrels" offers a variety of options. Add your city for local resources.) Opaque is good; clear containers that light can penetrate facilitates algae growth. Lids are good, but should fit tightly and not come off unintentionally. Being able to occasionally up-end the barrel to rinse out the bottom is a good idea, especially if you have an asphalt roof.
  2. Wash it out with soap and water.
  3. Cut a hole in the top for the downspout.
  4. Cut the downspout to just about touch the hole in the rain barrel. Place a screen over the hole to catch debris for easy cleaning.
  5. Drill a 15/16" hole in the base. Add a Y-connector that has a valve on each branch of the Y. One connector is for your hose and the other will work as an overflow valve. You can attach another hose to the overflow and route it into your garden.
  6. For extra water pressure, mount the barrel on a stable platform or blocks. (Fasten it to something stationary to prevent tipping.)


Rain barrels are big, heavy, and potentially hazardous.


Rain barrels are not known for their visual appeal. If you find that it offends your sensibilities, consider making a two-sided lath screen. Two panels about 2'x4' can be hinged in the middle and placed to camouflage your rain barrel, but not get in your way when you need to get to it.


Mother Earth News—Mother Earth News has been around for years and still manages to produce useful information for those concerned about the environment, interested in simplifying their lifestyle, or reducing their impact on the planet.

In addition to rain barrels, consider adding a rain garden. Hire a qualified landscape contractor through UpdateRenovate to help.

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