# Rain Barrels of Fun

How much water will your roof yield? : • Determine the portion of roof that drains to your downspout.
• Determine the roof drainage area (length x width) in feet for square feet.
• Roof square feet x inches of rainfall x 0.6 = gallons of water collected.
 Example: 1. Roof drainage area is 24’ x 20’. This is equal to 480 square feet. 2. Rainfall event is 0.25 inches. 3. Gallons of water collected can be calculated: - 480 sq ft x 0.25 inches x 0.6 = 72 gallons of water

How much do I need? :

• Determine the area of your garden (length x width) in feet for square feet.
• Determine the amount of water desired in inches. (0.25 inches is a good amount for watering)
• Garden square feet  x  inches  x  0.6 = gallons needed
 Example: 1. Garden area is 10’ x 35’. This is equal to 350 square feet. 2. Water needed is 0.25 inches. 3. Gallons needed: - 350 sq ft x 0.25 inches x 0.6 = 52.5 gallons of water

How much area will my collected water cover? :

• Estimate the gallons of water collected.
• Determine the amount of water desired in inches.
• Gallons collected (divided by)  inches of water desired (divided by) 0.6 =  Square foot area that can be watered
 Example: 1. 55 gallons (1 barrel) collected. 2. Would like to water equal to a 0.25” rainfall 3. Area that can be watered: - 55 gallons (divided by) 0.25 (divided by) 0.6 = 366 sq foot area

Why do we use 0.6 to convert square feet to gallons?

1 cubic foot of liquid = 7.48052 gallons (standard conversion)
1 cubic foot = 12” x 12” x 12”
We are only using 1 “ of a cubic foot which is 1/12 of the cubic foot.
7.48052 12 = 0.623 gallons