Estimate runoff and storage for your site
Explore how your site area, rainfall and soil assumptions affect runoff and an initial storage estimate. Start with the site inputs below, then adjust the storage assumptions to compare options.
- Free to use
- No sign-up needed
Before you start
This existing calculator uses IH124 for runoff and a simplified one-hour rainfall scenario for storage. Check any suggested rainfall and soil values against your site information. The storage result is an early estimate; it does not test critical storm durations or size a drainage network.
Surface water drainage advice →Calculate Runoff Rates
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Planning drainage for your site?
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