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Rain Barrel Overflow

Thinking about Overflow

Before you decide to purchase a rain barrel, decide whether or not it is appropriate to disconnect your downspout. Occasionally, your rain barrel will overflow. During a half-inch rainfall, 310 gallons of water run off a 1,000 square foot roof. If the roof has 4 downspouts each accepting roughly the same amount of water, one downspout will accept 75 gallons, causing the barrel to overflow by 25 gallons. In larger rain events, or if the barrel already holds water, it will overflow even more. Consider where you are directing that water:

  • Consider planting trees and other leafy, deep-rooted plants nearby.
  • Consider the slope of your yard. Overflow should not run toward your foundation or onto your neighbor’s property.
  • Stormwater should not flow over walkways since the water may freeze in cold weather and cause slippery conditions.

Dealing with Overflow

You can install an overflow drain on the side of the barrel near the top, and attach an overflow hose to the fitting. An overflow drain will direct excess water away from the foundation and towards plants or trees that you want to water. You can attach the overflow hose into the opening of another barrel if you need increased storage for your rainwater. In any case, your rain barrel or the last rain barrel in your series of connected barrels should have a hose to direct water away from your foundation. A rain garden or tree base are good places to direct your overflow because of the long roots. Do not direct overflow to paved or impermeable surfaces.

Downspout Diverters

One way of dealing with excess overflow is to purchase a downspout diverter. There are a couple of types of diverters. Some styles will push excess water in your barrel up from the rain barrel into the downspout diverter and back into the original gutter system. Others will lead some of the water from the downspout to the gutter while channeling some into a rain barrel. Downspout diverters are available through Upcycle Products or Matty K’s. If you know of another Chicago retail location offering diverters, please contact info@sustainablebackyards.org so we can add them to our list!