Rainwater Harvesting Calculator
Estimate annual rainwater collection potential based on roof area and local rainfall.
Annual Rainwater Collected
29,904 gallons
Annual Rainwater Collected vs Collection Roof Area
सूत्र
## How to Calculate Rainwater Collection Rainwater harvesting captures roof runoff for irrigation, toilet flushing, or other non-potable uses. ### Formula **Gallons = Roof Area (sq ft) * Rainfall (inches) * 0.623 * Collection Efficiency** The factor 0.623 converts 1 inch of rain on 1 sq ft to gallons. Efficiency accounts for gutter losses, first-flush diversion, and evaporation.
हल किया गया उदाहरण
1,500 sq ft roof in an area with 40 inches annual rainfall, 80% collection efficiency, $5/1000 gal water cost.
- 01Annual collection: 1,500 * 40 * 0.623 * 0.80 = 29,904 gallons
- 02Monthly average: 29,904 / 12 = 2,492 gallons
- 03Annual savings: 29,904 * $5 / 1,000 = $150
- 04Recommended tank: ceil(2,492 / 100) * 100 = 2,500 gallons
अक्सर पूछे जाने वाले प्रश्न
Is rainwater harvesting legal?
Most US states allow rainwater harvesting. Some states like Texas and Oregon actively encourage it with tax incentives. A few arid states have restrictions, so check local regulations.
How much rain can I collect from 1,000 sq ft?
One inch of rain on 1,000 sq ft yields about 623 gallons. At 80% efficiency, that is about 498 usable gallons per inch of rainfall.
Can I drink collected rainwater?
Rainwater can be made potable with proper filtration and UV/chemical treatment, but most residential systems use it for irrigation, toilet flushing, and laundry.