How Do I Plan For A Sewage Treatment Plant?

If you’re considering installing a sewage treatment plant, there are several planning considerations for you to bear in mind. This guide from Owls Hall Environmental addresses some of the most important things to plan for.

Where can I discharge sewage water to?

Wastewater treatment plants produce discharge of sufficient quality to be discharged into a ditch or a watercourse. If the ditch is dry, then you may need to install a drainage field prior to the ditch to let the water percolate through the ground before entering the ditch.

If the waste is from a septic tank, then you cannot discharge to a ditch or watercourse and you will require a drainage field.

How much power is needed to run a sewage treatment plant?

Values vary between models; however there are plants that operate on the equivalent of a 60 watt light bulb. Please refer to the manufacturer’s guideline for details or contact us on 01844 877030 for more information.

How much does a sewage treatment plant cost to run?

It varies between models, most domestic systems will use a 60w or 80watt compressor (or blower), with a power consumption of around 1.9kwh per day. At an average of 13 pence per Kwh this is: £0.25 per day (£91.25 per year).

Efficient SBR style treatment plants do not have to run all the time and cost less to run (around £40 a year for a family of four).

What size sewage treatment plant do I need?

This depends on the size of the property and number of its occupants. It goes without saying that the smaller the property, the smaller the treatment plant. However, you must size the treatment plant for its potential occupancy not how many people are there at the moment.

Sizing the treatment plant using British Water Flows and Loads guide is imperative.

A simple guide is:

Number of bedrooms Occupancy
1-3 5
4 6
5 7
6 8

Since treatment plants don’t always come in every occupancy size, you will have to choose the next size up. Therefore if you have a max occupancy of 7, you will have to choose a system suitable for 8 people. Never undersize a treatment plant (even if you have a 1 bedroom house).

If you require more detail, our “how to size a sewage treatment plant” goes into more depth about the subject.

Do I need my sewage treatment system commissioned?

Whilst some manufacturers don’t have any particular requirement to commission their systems, we would always recommend it if you can.

Even if you are having your system installed by a builder, you can contact a local service company and ask for a price for commissioning your treatment plant.

Commissioning usually consists of:

  • Detailed check over of the systems installation (levels etc)
  • Functionality checking or working components (pumps, blower)
  • Checking of ventilation system
  • Any programming of control panels (should there be one).

Having the system commissioned can give you some peace of mind that it has been installed correctly. We have seen many systems that have been installed incorrectly, commissioning is a good time to ensure it has been done right. It also gives you the opportunity to get to know your local service company and arrange a service contract to look after the system.