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How Much Rainwater Can You Collect?
Calculate rainwater collection potential from your roof area and local rainfall.
In this article
Calculate
Litres = roof area (m²) × rainfall (mm) × 0.9。 100 m² roof, 10mm rain: 900 litres! India avg: 700-1,200 mm/year。 100 m² roof: 63,000-108,000 litres/year!。 Storage tank: ₹5-15/litre capacity。
Mandatory
Chennai, Bangalore, Delhi, Hyderabad: rainwater harvesting mandatory。 Reduces water bill + legal compliance. Recharge pit: ₹5,000-15,000。
⚡ CalcWolf Insight
A single rain barrel saves approximately 1,300 gallons of tap water per year — about $15-20 on your water bill. The environmental benefit is larger: it reduces stormwater runoff (the #1 source of urban water pollution) by capturing roof water that would otherwise flow into storm drains carrying pollutants to local waterways.
Frequently asked questions
How much water?▾
100 m² roof: 63,000-108,000 litres/year! Significant。
Mandatory?▾
Many Indian cities: yes. Penalties for non-compliance in some areas。
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