For commercial properties or multiple properties outside the scope of this calculator, use British Water’s flows and loads guidance, contact the Environment Agency or contact us for advice.

Download ‘British Water: Flows and Loads – 4’ (PDF – 941KB)

For other information:  Septic tanks and treatment plants: permits and general binding rules

How is this calculation used?

This calculation is used to determine the size of a treatment plant or septic to be installed. So for instance if a single property with four bedrooms produces a estimated daily discharge of 0.90 cubic meters per day then a package sewage treatment plant (PSTP) that can process 0.90 cubic meters per day or greater would be required. Sometimes it is advisable to install a larger system than necessary in order to future proof the property i.e. if space exists to extend the property by adding additional bedrooms.

How we can help?

Contact us on  01772 846193 / 07968 143756 or fill in the contact form if you have any wastewater queries or require advice. We can advise on the installation of new systems and carry out maintenance work on your drains, drainage field, pump chamber, septic tank or package sewage treatment plant.