Septic tanks and sewage treatment plants: what you need to do
Your property has a new discharge
There are things you must do if your property has a ‘new discharge’ where you release sewage to the ground or to surface water.
You have a new discharge if one or more of the following apply:
- it has not yet started (for example, if you’re still in the planning stage of building a house or business)
- it started on or after 2 October 2023
- it changed in type (from ground to surface water, or the other way around) on or after 2 October 2023
- it has moved more than 10 metres on or after 2 October 2023
- since 2 October 2023 the discharge has increased to more than 2 cubic metres (2,000 litres) a day if it goes to ground or more than 5 cubic metres (5,000 litres) a day if it goes to surface water
If you buy a house that already has a septic tank or sewage treatment plant, check when it was installed to work out if it counts as new or existing.
Connect to a public foul sewer
If you have a new discharge it must be connected to a mains sewer (also called a ‘public foul sewer’), if the Environment Agency decide it is ‘reasonable’ to do so.
Read the guidance on ‘discharges in sewered areas’ to find out which criteria apply when connecting different types of property to a public foul sewer.
The Environment Agency will decide what’s reasonable based on:
- how close you are to a public foul sewer
- the cost of connecting to a public foul sewer compared with the cost of installing a sewage treatment system
- whether there’s anything in the landscape that would stop you connecting to the public sewer - for example a large road
- whether your sewage treatment system would have any environmental benefits - for example if it reuses treated effluent
The Environment Agency will not give you a permit for a sewage treatment system if it’s reasonable for you to connect to the public foul sewer.
If it’s not reasonable to connect to a public foul sewer you’ll need to install a sewage treatment system to deal with your sewage.
Installing a new sewage treatment system
You should only install a sewage treatment system if it’s not reasonable to connect to a public foul sewer.
You must have building regulations approval to install a new sewage treatment system.
You might also need to get planning permission. Check with your local council.
Check if you meet the general binding rules
If you already have or are installing a septic tank or treatment plant, and it is not reasonable to connect to a public foul sewer, check if it meets the ‘general binding rules’.
If you do not meet the general binding rules
You must try to meet the general binding rules, for example by changing your sewage treatment system.
If you cannot meet the general binding rules you must apply for a permit.