Rainwater Harvesting Calculator
Estimate annual collectible rainwater, daily coverage, and suggested tank size.
Roof catchment (sections)
| Section | Area (m²) | Runoff coeff (0–1) | Effective (m²) | |
|---|---|---|---|---|
| — | ||||
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Total effective catchment
— m²
Overall system efficiency
—
Runoff × System × First flush
Rain & usage parameters
1 mm over 1 m² = 1 liter
Harvestable water (annual)
— L/yr
— m³/yr
Average per day (from rain)
— L/day
Household demand
— L/day
— % coverage
Suggested tank size
— L
— L for dry months buffer