<p>Total cistern volume can be estimated by multiplying the depth of design storm the catchment area. <br>1 mm of rain over 1 m<sup>2</sup> results in 1 L of runoff. <br>
<p>Total cistern volume can be estimated by multiplying the depth of design storm the catchment area. <br>One millimeter of rain landing on 1 m<sup>2</sup> results in 1 L of runoff. <br>
For example, the 90th percentile event in Barrie is 26 mm, so every 1 m<sup>2</sup> of rooftop will generate 26 L during this storm event. A 2000 m<sup>2</sup> building would generate 54,000 L of runoff.
For example, the 90th percentile event in Barrie is 26 mm, so every 1 m<sup>2</sup> of rooftop will generate 26 L during this storm event and a 2000 m<sup>2</sup> building generates 54,000 L of runoff. <br>