Rain Barrels of Fun

How much water will your roof yield? :rainwater barrel

  • 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