Does roof pitch matter?
For collection volume, only the horizontal footprint matters, not the slope area. A steeper roof has the same footprint as a flat one covering the same building.
Calculator
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Analysis
Interpretation of the current calculator output
Enter values to see detailed analysis and insights.
How to Use
Step-by-step instructions
- 1Enter the footprint area of your roof (length x width).
- 2Enter the rainfall amount (e.g., annual average or a single storm event).
- 3The calculator will estimate the harvestable water.
Harvest Potential
Calculates gallons harvested based on roof area (sq ft) and rainfall (inches). Includes a 0.623 conversion factor and 90% efficiency.
Gallons = Area x Rainfall x 0.623 x 0.9Variables:
AreaRoof footprint (sq ft)RainfallInches of rain0.623Gallons per inch per sq ftExample
1000 sq ft Roof
Inputs:
Area:1000 sq ft
Rainfall:1 inch
Steps:
- 1.Gallons = 1000 * 1 * 0.623 * 0.9 = 560.7 gallons
Result:
561 Gallons