Project Guide

How to Use a Rain Barrel

Difficulty: BeginnerTime: 2-4 hours Print

Water can be scarce in some parts of the United States and the rest of the world. Collecting rainwater provides gallons of free water. Use rainwater to water your plants, wash your car and more without increasing your water bill. This guide reviews how to use a rain barrel, including the steps for building your own and keeping it clean.

Tip: Some locations require permits for rainwater harvesting or prohibit rain barrels outright. Others offer financial incentives for using rain barrel water. Check local regulations to learn the rules in your area.


  • Cleaning Pails
  • Power Drill
  • Work Gloves


  • Sealants
  • Trash Can Lids
  • Rain Barrels
  • Garden Hoses
  • Landscape Fabric
  • Hose Bibbs

1. How to Use Collected Rainwater

A person uses water from a rain barrel to fill a watering can.

  • Rainwater flows over a roof surface. It can absorb bacteria, chemicals and other pollutants, so until it’s treated, you can’t drink it.  If you choose to use collected rainwater for drinking, make sure you thoroughly treat it first.
  • An untreated water supply has many uses. Rain-barrel water uses include watering your lawn or gardens, washing your car, cleaning outdoor items or even filling a toilet.
  • You don’t need to treat rainwater to water a vegetable garden, but make sure to pour only onto the soil and not the plants.

2. Before Making a Rain Barrel

A rain barrel is placed on a raised stand to improve water flow.

You can purchase the components in a rain barrel kit, but building a DIY rain barrel is simple.

  • Begin with a 55-gallon barrel or plastic drum. Make sure the barrel is food-grade plastic so the water won’t be contaminated.
  • Choose a location for the rain barrel, ideally beneath your gutters’ downspout that’s closest to your garden or where you’ll need the water.
  • Make sure that your rain barrel will be on a flat surface that can support the weight of a full barrel, which can be up to 300 lbs.
  • An elevated surface will raise the flow rate of the barrel’s water, so consider placing the barrel on a platform on cinder blocks.

3. Making the Rain Barrel

A person attaches a spigot near the base of a rain barrel.

  • With the barrel on its side, use a power drill with a 1-inch drill bit to drill a hole about 5 inches above the base of the barrel for the drain.
  • Drill an additional hole about 3 inches below the top of the barrel for the overflow.
  • Insert a hose bibb or spigot in the drain hole. Then, place metal and rubber washers and waterproof sealant on both the inside and outside of the barrel. This will keep it watertight.
  • Do the same to attach a spigot or hose connector to the overflow. The overflow should have a hose that feeds to an appropriate runoff place on your property. You can also use a back-up rain barrel for overflow. Be sure the second barrel also has an overflow and runoff option.

Tip: Some rain barrels include a pump to increase the flow rate.

4. Attaching the Rain Barrel

Water flows from a downspout into a rain barrel that has a small flowerbed built into the lid.

  • Cut or drill a hole in the rain barrel lid large enough for the downspout or diverter to fit.
  • Shorten or adjust your downspout as necessary. Use metal snips to cut the downspout to the appropriate length. Add an elbow section if needed.
  • Cover the inside of the barrel with a debris filter such as landscape fabric or a large piece of mesh window screen. This keeps mosquitoes from laying eggs and keeps other contaminants out of the water supply.
  • Close the lid. If a lid doesn’t come with the barrel, use plywood or a trash can lid to cover the barrel.

Tip: A flat-back rain barrel can fit more snugly against the side of your house, taking up less space.

5. Cleaning a Rain Barrel

A person sprays water to clean the inside of a plastic barrel.

  • Collected rainwater can grow stagnant, so use the water and empty the barrel within a week after it rains.
  • Clean the rain barrel once a year.
  • Disconnect from the barrel from the system and turn upside down to drain completely.
  • Rinse inside with a hose. Wear gloves to remove any sediment or decaying materials from openings.
  • Use a bucket to make a sudsy solution of water and dish soap.
  • Clean the outside of the barrel with a sponge and soapy water.
  • Clean the inside of the barrel with a mop or broom and soapy water.
  • Empty the barrel and let it dry. Then, put it back in place and reattach to the downspout.


During one inch of rainfall, a rain barrel can gather up to a half-gallon of water per square foot of roof. Rainwater collection is an efficient way to conserve water and reduce stormwater runoff. Make use of stored rainwater and see a reduction in your water bills.uring one inch of rainfall, a rain barrel can gather up to a half-gallon of water per square foot of roof. Rainwater collection is an efficient way to conserve water and reduce stormwater runoff. Make use of stored rainwater and see a reduction in your water bills.

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