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Calcimator

Rainwater Collection Calculator

Size rainwater harvesting tanks and estimate annual collection based on roof area, rainfall, and usage patterns.

Inputs

Results

Net Annual Collection

92,319 gal

Recommended Tank Size

4,200 gal

Days of Supply462 days
Pump Size10 GPM
How to Use This Calculator
  1. Enter Roof Area (sq ft), Annual Rainfall (in), and Daily Usage (gal).
  2. Set First Flush Diverter (gal).
  3. Review Net Annual Collection (gal) and Recommended Tank Size (gal).
  4. Use Days of Supply (days) and Pump Size (GPM) to inform your decision.
  5. Use the chart to visualize the results and explore different scenarios by adjusting inputs.
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