Hammer CalculatorCalculators / Landscaping / Rainwater Harvesting Calculator
Rainwater Harvesting Calculator
Estimate how many gallons your roof can collect each year, find the right storage capacity, and compare costs across rain barrels, IBC totes, and underground cisterns.
Rainwater Harvesting Calculator
Container Pricing (edit to match local rates)
Annual Collection
29,904 gal
2,492 gal/month avg
Days of Supply
598 days
at 50 gal/day usage
Recommended Storage
2,492 gal
~1 month buffer
Lowest Cost
$2,000.00
10 totes
| Purchase Option | Quantity | Est. Cost |
|---|---|---|
| Rain Barrels | 46 × 55 gal (2,530 gal total) | $5,520.00 |
| IBC TotesBest value | 10 × 275 gal (2,750 gal total) | $2,000.00 |
| Underground Cisterns | 5 × 500 gal (2,500 gal total) | $4,000.00 |
Best value: IBC Totes — $2,000.00Your roof can collect approximately 29,904 gallons per year. At 50 gallons/day, that covers about 598 days of use. The most affordable storage option is 10 totes (2,750 gal total capacity) for $2,000.00.
Install a first-flush diverterThe first rain after a dry spell washes dust, pollen, bird droppings, and other contaminants off your roof. A first-flush diverter discards the first 1-2 gallons per 100 sq ft of roof before directing cleaner water into your storage. This is especially important if you plan to use the water for edible gardens.
This is a rough estimate only. Actual collection depends on roof material, slope, gutter efficiency, seasonal rainfall distribution, and local regulations. Some areas require permits for rainwater collection or restrict the total volume stored. Check local codes before installing.