Calculating tools

Here are some handy tools for you to calculate rainwater storage potential

 
First up, click here (or the image below) to go to our online calculator tool which will automatically determine the tank size you require and the ongoing savings you can expect from your rainwater harvesting system:

RainCatcher - Rainwater Harvesting Calculator

The manual example calculations in the PDFs below will also assist you in determining appropriate tank sizes and payback periods.

Example calculations (domestic)   /   Example calculations (non-domestic)
RainCatcher - Example Domestic Rainwater Harvesting Usage     RainCatcher - Example Domestic Rainwater Harvesting Usage

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Commercial rainwater harvesting design form here
Domestic rainwater harvesting design form here
 

This information sheet contains a formula to help you measure your roof catchment area.

RainCatcher - Training Guide

The Met Office link below will give you the rain fall in your area, this can then be used to help size your rainwater storage tank accurately:
http://www.metoffice.gov.uk/climate/uk/summaries/2015/annual/regional-values