Project Guide

How to Use a Rain Barrel

How to Use Collected Rainwater
A person uses water from a rain barrel to fill a watering can.
  • Rainwater flows over a roof surface and can absorb bacteria, chemicals from the roofing materials and other pollutants, so consider it non-potable until treating it. If you elect to use collected water for drinking, make sure you thoroughly treat it before consumption.
  • A non-treated water supply has many uses. Rain-barrel water uses include irrigating your lawn, gardens or flower bed; rinsing off your windows or driveway; washing your car; or even filling a toilet. 
  • You don’t need to treat rainwater to irrigate a vegetable garden, but make sure to water the soil and not the plants themselves. 
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 a building a DIY rain barrel is a relatively simple project. 

  • Begin with a 55-gallon barrel or plastic drum. Make sure the barrel is food-grade plastic so unwelcome chemicals do not contaminate the water. 
  • 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
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, placing metal and rubber washers and waterproof sealant on both the inside and outside of the barrel, to ensure it remains water tight. 
  • 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, or even a back-up rain barrel, as long as that barrel also has an overflow and runoff option. 

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

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. You may need to 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 to prevent mosquitos from laying eggs and other particles from contaminating 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. 

Cleaning a Rain Barrel
A person sprays water to clean the inside of a plastic barrel.
  • Collected rainwater can grow stagnant, so empty the barrel, making use of the water, within a week of rainfall. 
  • 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. Use 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.R
  • Empty the barrel and allow it to dry before putting it back in place and reattaching 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 a highly efficient way to save on water bills, irrigate your yard or garden, conserve water and reduce stormwater runoff.