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Rainwater Harvesting Calculator

Enter the roof area and your yearly rainfall to estimate how much water you can store.

Enter your details

mm
Look up your city. Quetta is roughly 250 mm.
litres

SARZAMEEN Tools | Rainwater Harvesting Calculator

Estimate generated 19 Oct 2026 | https://www.property.candletrack.pro/public/buildcraft/tool/rainwater-harvesting-calculator

Results

Enter your values and press Calculate. Results will appear here and update as you change inputs.

    Rainfall varies from year to year. Treat harvested water before drinking.

    How this calculator works

    • Water = roof area (m²) × rainfall (mm) × runoff factor × 0.9 (first-flush loss).
    • Runoff factor: concrete 0.8, tiles 0.75, metal 0.9.

    Frequently asked questions

    Not without filtering and disinfecting. It is mainly used for gardens, cleaning and flushing.

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