How Rain Barrels Work

Rain barrels are containers designed to trap and store rainwater. They can be huge, complex systems that use pumps and linked barrels for storage, or single plastic or wooden drums that catch rainwater swirling along roof gutters and out of downspouts.

Harvesting rainwater makes good sense. It doesn’t contain the dissolved minerals and salts typically found in the well water you might be using to supplement your outdoor water needs. It’s safe — if you follow a few precautions — and rain barrels are easy to make and install. Using rain­water also helps the environment. Need more encouragement for installing your own rain barrel? In Germany and Japan, there are monetary incentives for rainwater harvesting; Arizona and California also have programs available.

Rain is a good source of water that would otherwise become polluted runoff picking up chemicals and other dangerous waste as it carom­s down streets and gutters on its way to a network of storm drains or the nearest low-lying body of water. In many areas, rainwater harvested from the roof of an average home can go a long way toward providing the water needed to maintain a vegetable garden or your home’s landscaping over the summer months.

The Advantages of Using Rainwater

Rainwater is relatively pure stuff. The process of evaporation leaves chemicals behind, and what you see falling from the clouds starts out pretty clean. It picks up particulates, pollution, pollen and dust as it makes its way to the ground, but even those contaminants become less of an issue if it’s been raining for a while and the air is cleaned with a good water scrubbing.


Evaporation is nature’s distillation process, and the fresh water you’re drinking out of the faucet was a raindrop at some time — maybe a number of times — in its long history on the planet. It’s true that tap water has been treated with chlorine and other chemicals to make it safe to drink, but for nondrinking uses, rainwater is a good, wholesom­e choice.


Besides being natural, rainwater is usually soft, which makes it a good option for watering your flowers and plants. Actually, the absence of those very chemicals that make tap water safe for drinking makes rainwater a better choice for your outdoor watering needs.


Supplementing your water needs with rainwater will reduce your utility bills, at least during the summer months. It will also reduce the drain on groundwater resources. As communities grow, the demand for water can outstrip the supply. Municipal water districts often rely on groundwater or aquifers that can become overtaxed. Supplementing our collective water needs with a little rainwater can help postpone the costly expansion of water treatment facilities groaning under the weight of population growth, an aging infrastructure and urban sprawl.


In some areas, using rainwater may mean the difference between keeping your lawn and plants alive or watching them die of thirst. In times of drought, when there are restrictions on water use, rainwater may be the only available source of water for landscaping and washing the family car. It may come down to a choice between rainwater and no water at all.


Reducing the demand for water helps protect the local ecology, too. Water that isn’t being diverted into municipal water systems stays in the lakes and river­s to sustain fish, birds and other wildlife. Besides relaxing some of the demand on existing water resources, harvesting rainwater reduces the amount of polluted rainwater runoff. Dirty rainwater is often released from storm drains directly into lakes and streams, causing big problems for plants and animals. Imagine the chemical stew you see on the roadways, like oil and antifreeze, washing directly into your favorite brook or creek.

Choosing a Rain Barrel

There are things to consider before installing a rain barrel. Because the rainwater you plan on harvesting is running off your roof, ther­e are safety concerns. Some roofing materials will contaminate rainwater and make it dangerous to use. You should not use roof catchment areas that incorporate asbestos shingles, tar and gravel, or treated cedar shakes. You should also check your gutters to make sure that they don’t use lead solder or lead based paints.

Once you know that you can harvest rainwater safely, you need to evaluate how much water you want to capture, and how you want your system to look. Although there are many different styles and designs available, a large aboveground system will take up quite a bit of space in your flowerbed and can get expensive, so it’s important to understand what you want and have a budget in mind before you go shopping. You should ask yourself if you plan on watering your lawn, washing your car or maintaining your vegetable garden with your rainwater reserves. Activities like watering the lawn can consume lots of water, so do your homework. Check your water bills from last few summers to determine how much water you use during the peak summer months and plan from there.

Any system you select or build will need a tight-fitting lid to keep animals out and discourage the development of algae. It should also be made of quality material like food grade plastic that’s UV protected and have a fine mesh screen to reduce the amount of debris in the water and keep mosquitoes from using the standing water as a breeding ground.


To keep the foundation of your home safe from water damage, it’s important that your rain barrel have an automatic overflow mechanism that diverts water back into the downspout once the barrel has been filled or to an overflow hose that drains downhill away from your home.


Other considerations for convenience a­nd water quality are water filtration systems, UV lights to kill bacteria and pumps to make water distribution easier. There are also special diverters available that will block the initial water flow in a rainstorm from going into the rain barrel. After the initial flow washes the dirt out of the air and off the roof, the diverter reroutes water back into the barrel.