A rain barrel is a very simple way to reduce runoff on your property. When placed under a downspout, it collects the water that drains off the roof, via gutters, during a rain event. Not only can this reduce erosion and sedimentation on your property, but since the water in the barrel can be used to water your plants or gardens, it also reduces your water consumption.
The main limitation of the rain barrel is its capacity. The average rain barrel can hold 55 gallons, which is the approximate amount of water produced by 1 inch of rain falling on a 10 foot by 10 foot area of roof. Numerous rain barrels can be used for a single roof by placing 1 at each downspout. If a single barrel is not enough to accommodate the water from a downspout, you may equip the barrel with an overflow hose to redirect the excess, or connect multiple barrels with hoses to increase their capacity.
A rain bench is a similar concept, but stores the water in a large plastic bladder inside a wooden bench structure. The bladder has a 65-gallon capacity, but you can use 2 bladders, for example, and simply double the size of the bench. With large houses, though, you may want to consider a larger-scale, landscaping-type solution.
Determine Necessary Size
In order to
determine the rain barrel or bench capacity necessary to capture the
runoff from your roof, calculate the area (in square feet) of your roof
that drains to each downspout, and divide that number by 100 (the number
of square feet of roof that can be drained to a single rain barrel or
bench). Note: roof area is simply a measure of horizontal length
and width; there is no need to take the slope of the roof into account
since the roof, from above, has only2 dimensions.
Rain barrels can be purchased online or from commercial retailers in more decorative styles. Costs usually vary from $100-$200. For the rain bench, each do-it-yourself kit costs $70, and the lumber costs an additional $30. A double capacity rain bench would cost about $200.