How to Collect Rainwater With Water Barrels

Medically Reviewed by Jabeen Begum, MD on November 03, 2022
Written by Jeannie Myers
6 min read

A rain barrel is a large container placed under a downspout to collect rain as it runs off your roof. Usually, a rainwater barrel will have an overflow valve, a screen or filter to keep out bugs, and a tap near the base. You can turn the tap on to fill buckets for washing cars or windows or connect a soaker hose to the tap to water your flowers and lawn. According to the Environmental Protection Agency (EPA), most U.S. homeowners use more water outside than they do for showering and laundry combined. Collecting rainwater can help lower your water bill and provide chlorine-free water for your plants.

It's easier and faster to buy a ready-to-use rain barrel from a garden center or hardware store, but it's cheaper to make one. There are do-it-yourself instructions available online. Many cities and counties offer cheap rain barrels for sale or host workshops that provide materials and tools and teach you how to make your own rain barrel. 

Safety. Make sure that any openings on your rain barrel are small enough that a young child can't fall into or crawl inside.

Pest control. You don't want your rain barrel to become a breeding ground for mosquitos. Use a covered barrel or cover openings with a screen to keep out bugs. A fine mesh will keep insects from getting into the barrel and laying eggs.

Algae prevention. To prevent algae, choose a barrel made of dark, opaque material. Opaque means you can't see through it at all, which will make it hard for algae to get the sunlight it needs to grow. If at all possible, set up your rain barrel in a shady place or on the side of the house that gets the least direct sunlight.

Overflow. Decide where you want the water to go if a big storm overfills the barrel. You don't want all that extra water pooling next to the foundation of your house. Find a place in your yard where the water can soak into the soil or run downhill away from the house. Get a water hose that's the right length to direct water to the place you've chosen.

  1. Level the surface under the downspout. A full rain barrel is extremely heavy. If a child tries to climb on the barrel and accidentally tips it over, they could be badly hurt. The rain barrel must rest on a stable, steady surface.
  2. Elevate the rain barrel by building a low platform out of bricks, cinder blocks, or decorative stones. Your goal is to raise the tap high enough so you can easily fit a bucket or watering can under it. Getting the rain barrel up off the ground will also increase the water pressure, making the water flow out of the tank more quickly.
  3. Remove the elbow, the bent piece at the bottom of the downspout. Place the rain barrel on the platform and hold a flexible elbow up to the downspout. Mark where you need to cut the downspout so that there will be 2 inches of clearance between the end of the flexible elbow and the rain barrel. This allows the rain barrel to be removed for cleaning or maintenance.
  4. Use a hacksaw to cut the downspout at the mark. Save the piece of downspout you cut off — you'll need to be able to reattach it in the winter. Settle the rain barrel on its platform. Attach the flexible elbow to the downspout on the house and bend it so that the rainwater will flow into the barrel. Finally, attach the hose to the overflow valve and arrange it so any extra water is directed away from the house.
  • Try to use the water in the rain barrel often so there is room for the water from the next rainstorm.
  • Keep gutters and downspouts clear of debris to prevent clogging and bacteria growth.
  • Each winter, before the first freeze, completely empty the rain barrel. Straighten the flexible elbow and use it to put the old downspout back on. Turn your rain barrel upside down or store it in a sheltered place like a shed. This will keep it from freezing and cracking.
  • Once in a while, remove the lid or screen and clean out the inside of your rain barrel with a scrub brush.
  • If algae start growing in your rain barrel, empty out the water and scrub out the inside of the barrel with a mix of 3/4 bleach to 1 gallon of water. Rinse it out very well and dump the bleach water into a tub or shower drain.
  • If your rain barrel has a screen to keep out leaves and mosquitos, keep it clear and clean. Check it for holes or rips, as it may need to be replaced from time to time.

Do not drink water from a rain barrel. Three reasons drinking from a rain barrel is risky:

Germs.Bacteria, viruses, parasites, and fungi can wash into your rain barrel — sometimes from bird poop on the roof or in the gutters. Germs also grow in standing water. People have gotten sick from drinking collected rainwater.

Chemicals. As the water flows over your roof, it can collect harmful chemicals such as lead, copper, and asbestos. This is especially likely if your roof is:

  • made of copper 
  • made with wood shingles treated with a chemical known as CCA
  • treated with chemicals or zinc strips to prevent the growth of moss or algae

Pollution. Dust, smoke, and other forms of air pollution can get into rainwater before it hits your roof and flows into your rain barrel.

A rain barrel filter can remove some of the dangerous germs and chemicals, but the CDC recommends that you use city water or bottled water for:

  • drinking
  • cooking
  • washing dishes
  • brushing your teeth
  • watering any plant you will eat from, such as vegetables, fruits, and herbs

Free water. Each homeowner who uses a water barrel for rainwater collection can save up to 1300 gallons a year. That can save you money on your city water bill or lower the amount of drinkable well water you have to use for outside chores.

Healthier plants. Rainwater can improve the health of trees, bushes, flowers, grass, and houseplants. City water and well water are usually hard — heavy in minerals — and must be softened by adding chemicals such as calcium and lime. Rainwater is naturally soft, which plants prefer. In addition, chemicals like fluoride and chlorine are added to drinking water. These chemicals can damage sensitive plants and make the soil less healthy. Rainwater is free of fluoride, chlorine, and other additives, so it's a better source of water for your yard.

Spotless cleaning. Because it is free of added minerals and naturally soft, rainwater is also great for washing your car and the windows of your home. Hard water leaves spots behind, especially on glass, while soft water helps soap lather and rinses it away easily.

Less flooding. Collecting rainwater can reduce flooding in your yard and basement and decrease the amount of moisture around the foundation of your house.

Good stewardship. Rain barrels hold back some of the water that would otherwise rush downstream during a storm. The ground can only hold so much water at a time. In heavy rains, storm runoff carries animal waste, pesticides, fertilizer, oil, grease, and other pollutants into nearby streams, rivers, and lakes. This can harm fish, plants, and other wildlife. When you use stored rainwater in your yard, it slowly seeps into the ground and replenishes the groundwater reserves rather than washing away with the rest of the stormwater.