How to Use a Rain Barrel in a Garden

How much water can you collect? How long does it last? How much does a rain barrel cost? What should you look for when buying one? Here are the basics.

by Jessica Walliser
PHOTO: Jessica Walliser

A rain barrel should be on every gardener’s wish list. While it might not feel like collecting rainwater makes that much difference in your water bill, it does. An inch of rain on a 1,000-foot surface collects about 500 gallons of water. If you live where it rains even a moderate amount, that’s a lot of water you won’t pay for. Here are some basic facts about proper rain barrel use.

The Benefits of a Rain Barrel

  • Rainwater is better for plants. It prevents the salt build up that can occur when using chlorinated, softened tap water.
  • Rainwater doesn’t negatively impact beneficial soil life as chlorinated tap water can.
  • Collecting rainwater keeps it out of storm sewers and limits run-off.
  • Rainwater is free.
  • Rainwater has a pH that’s better for plants than most tap water.
  • Using rainwater to irrigate plants translates to a lower water bill.

What to Consider in a Rain Barrel

Don’t start shopping for a rain barrel until you check with your local government officials to make sure setting one up is legal in your hometown. Unfortunately, some communities and homeowner associations do not allow for the use of rain barrels. Others have very specific requirements you’ll need to follow for the design, size and placement of your rain barrel.

Good Traits for a Rain Barrel

  1. A built-in spigot to easily connect your hose.
  2. Made from a durable material that will last many years.
  3. An overflow outlet that lets you connect multiple rain barrels together.
  4. A downspout diverter that lets you close the opening of the barrel and divert the rainwater back down the rest of the downspout when the barrel is full.
  5. A screened or fully enclosed top to keep curious kids, animals and mosquitoes out of your rain barrel.
  6. Food-grade plastic, wood or a non-reactive metal is best if you’ll be using the water to irrigate food crops.
  7. Don’t use a barrel that was previously used to store oil-based products, chemicals, or if it’s made from recycled, scrap lumber that could have been treated with synthetic chemical-based wood preservatives.
  8. Frost-proof materials are best so you don’t have to worry about the rain barrel cracking in cold winter weather.
  9. A mesh screen where the water enters the barrel to filter out debris.
  10. Feet or legs that elevate the barrel to make emptying easier. If it doesn’t have feet, plan to prop the barrel up on concrete blocs so it sits a few feet above the ground and raises the level of the spigot above the height of your watering can.

Rain Barrel Concerns

Many gardeners would love to have a rain barrel but still have a few questions. Here are answers to the most common rain barrel questions.

What about mosquitoes?

Make sure the rain barrel opening is fully screened or sealed. If you still get mosquito larvae living in your rain barrel, drop in a ring-shaped dunk of the biological insecticide Bti (Bacillius thuringiensis israelensis) every 30-60 days. This kills mosquito larvae without dangerous chemicals and in a way that’s safe for the plants you’ll be using the water on.

Do I have to store my rain barrel indoors for the winter?

If your barrel is made of a frost-proof material, no. You can leave it in place. If the barrel is not frost-proof, you’ll have to either cover it with a tarp or move it into a shed or garage for the winter. But, regardless of what the barrel is made of, you’ll need to drain and empty the rain barrel at the end of each growing season. Yes, this should be done even if the material is frost-proof. After draining, close the downspout diverter to keep more water from coming into the barrel during the winter months. Then, open the spigot to release any water trapped inside of it.

Are rain barrels expensive?

They can be. Some models have all the bells and whistles and are quite expensive, while others are not. Shop around to find the best model and price for you. My rain barrel is an old wooden wine barrel with a spigot added to the base. It didn’t cost me much. You can also convert a food-grade plastic 55 gallon drum into a rain barrel using these plans for little to no cost. Or, go with a fancier, up-scale rain barrel if it’s better suited to your garden’s style and budget.

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If I can’t use the water in the barrel quickly enough, will it get “funky” and kill my plants?

No. Even if the water sits stagnant in your rain barrel for a long time, you can still use it to water plants. It might develop algae, but as long as there are no decomposing leaves or other debris in the barrel, the water will be fine to use. You should never drink the water from a rain barrel, though, no matter how old or new it is.

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