Building and Developing

How do I calculate my sewage flow rate?

Sewage flow rate

The average foul flow rate for a domestic house is 0.046 litres per second. For commercial or industrial properties this will vary, so will be calculated as part of the assessment we undertake.

We'll calculate the surface water flow rate. On your application, please indicate the total impermeable area (roof, paved, hardstanding area) that will be collecting rainwater in metres squared.