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Rainwater Harvesting Calculator

Estimate collectable rainwater from roof area, rainfall depth and collection efficiency.

How it works

Estimate collectable rainwater from roof area, rainfall depth and collection efficiency.

Formula:
Collected litres = roof area × rainfall(mm) × efficiency.

Before you use the result: Local rainfall data, drainage criteria, soil behavior and excavation safety requirements can govern the design.

Practical use

Use project-specific rainfall, catchment, soil and excavation information. Drainage and excavation safety can be governed by local regulations and site conditions.

Keep units consistent with the source information.
Use project-specific densities, pack sizes and coverage rates where provided.
Round purchasing quantities to supplier packaging and delivery rules.

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