2007-01-03 P&R Packet - Laserfiche WebLink

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Rain Barrel Hydrology Lesson: Spring snowmelt and rains are usually plentiful. A rain gutter and extended downspout will help keep the water away from your house and minimize freeze thaw cycles that are dangerous for sidewalks and driveways. Because it is unlikely that your garden will be lacking in water at this time, the main spring-time function of rain barrels is to reduce the amount of stormwater running off of your property. Summer weather is more sporadic with unpredictable rainfall and hot dry spells. Rain barrels provide a way to balance watering needs during this time. Most storms deliver a ~ inch of rain, but 5 to 6 times per year we get a 1-inch deluge. Because the typical residential roof can collect a significant amount of rainfall, the amount of water saved depends on the capacity of your rain barrel{s). If you want to store water for irrigation between summer storms, you will need a rain barrel of adequate size. Connecting 2 or 3 barrels together or installing a barrel at more than one downspout is an easy way to multiply your storage capacity. To help plan your rain barrel set-up, consider the following: 1 inch of rain on 1 square foot of roof yields 0.6 gallons. 1 inch of rain onto a 10 ft x 10 ft. area (100 sq. ft) yields 60 gailons. Multiply the square footage of your roof that drains into each individual downspout by .6,,10. :UII" to get your roof runoff volume. Either use a single barrel and prepare for occasional overflows, or select a rain barrel that can link to another to collect as much rain as possible. Check our recommended web links for ideas on botfl options. Example: One side of a one-car garage is draining into the barrel. If that roof area is 15 ft x 20 ft (300 sq. ft.), then 1 inch of rain will yield 180 gallons of roof runoff into the barrel. A more common storm event only delivers ~ inch of rain, producing 45 gallons that will flow into the barrel. Page 2