Calculateur de Récupération d'Eau de Pluie Gratuit
Calculez le potentiel de récupération d'eau de pluie de votre toiture. Dimensionnez votre citerne et estimez les économies.
Annual Rainwater Collected
29,904 gallons
Annual Rainwater Collected vs Collection Roof Area
Formule
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.
Exemple Résolu
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
Questions Fréquentes
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.