The New England Seacoast area precipitation had increased to almost 60 inches of rain each year. Approximately 550 gallons of rain water can be collected for each 1,000 square feet of collection surface per inch of rain. To estimate amount collected in one year, take the square footage of the collection area/roof, divide by 1,000, multiply by 550 gallons and then multiply by the average rainfall for your area.

Long periods of rain will give you more water than you can use, causing excess to overflow. You can increase your usable harvest by using a larger container or by connecting multiple barrels together. You will be able to use rainwater longer during periods without rain. Besides collecting the rain in barrels, tanks, or cisterns, you can save some of this free rainwater by adding a Rain Garden to your yard to slowly recharge your ground water and decrease the storm runoff from your property.