Where does the runoff from your roof area go now?:
Sketch a site plan. You can obtain an aerial view of your property from “Google maps” as a starting point. Mark the locations of downspouts and roof lines, estimate the square footage of your roof and paved areas, and map where all these areas drain.
Where would you like to locate your rain barrel?
Install your rain barrel based on where you will use the water in your yard. Keep in mind that it may be possible to re-hang the gutter and move the downspout to a more desirable location. The rain barrel must be located at the base of one of the downspouts draining your roof gutter. This is the downspout you will work with.
Where does that downspout currently drain?
The downspout you will divert to your rain barrel probably drains into a drainpipe or to your yard. This is the storm water discharge point and is the same location where the rain barrel should overflow with excess water. Rainwater collection for external, non-potable uses such as irrigation, do not normally require a permit, but there are still design considerations to follow.
All rainwater collection systems should have an overflow to a safe disposal location. The average residential roof generates about 30,000 gallons of rainfall runoff every year, and an average 55 gallon rain barrel captures only a fraction of that – unless your redirect the captured water repeatedly during the year. Even if you have multiple rain barrels, you should have an overflow to a safe discharge location. If your rain barrel overflows into the drainpipe, be sure the overflow pipe is attached to the drainpipe opening. If the downspout to be connected to your rain barrel currently drains to a surface infiltration area in your yard, the overflow from your rain barrel should also
discharge to that location.
• The right rain barrel must be secured on a firm, level surface. A full 55-gallon rain barrel weighs over 400 lbs. and tipping is a risk if it’s unsecured or on uneven ground.
• The barrel must be structurally sound and should be a food-grade container made to hold liquid. Containers such as trash cans are not designed to withstand the pressure of the water.
• The barrel should have a lid and a sturdy fine mesh covering all openings to prevent mosquitoes and debris from getting inside.
• The water from the rain barrel should never be used for drinking, cooking, or other potable uses.
• Your rain barrel should have an overflow to a safe discharge point.
• If you use a moss-control product or other chemicals on your roof, be sure to use products that are garden-safe.
Larger or More Complex Systems
When there is no right rain barrel for your needs, a more complex rainwater collection systems might be necessary. These systems usually have a large storage container (a cistern), and use pumps to move water to desired locations. Some use their captured rain water indoors for toilet flushing,. These projects involve factors not applicable to simple rain barrels, such as plumbing and electrical work, soil excavation, or concrete foundations and other structural components. For rainwater collection projects of this scale, you should consult a professional to review design, construction, and safety considerations.