Private sewage treatment system registration variation guidance
This guidance helps you determine whether you need to apply for a variation to your existing registration for a private sewage treatment system, and whether a fee applies.
All discharges must be registered with SEPA.
Do you need a variation?
You do not need to apply for a variation if:
- You are adding extra rooms or toilets to your property.
- You are replacing a septic tank with a package treatment plant (PTP), and your registration already allows for a system that provides better treatment than a septic tank.
Example: Replacing a septic tank with a PTP is fine if your registration already covers improved treatment.
You must apply for a variation if:
- You change the name or address of the property.
- You change the location of the discharge (e.g., moving the outfall).
- You increase the population equivalent (PE) for non-domestic use.
Fees for variation applications
| Type of change | Variation required? | Fee applies? | Fee amount |
|---|---|---|---|
| Adding extra rooms or a toilet to a domestic property | No | No | |
| Population equivalent (p.e.) is being reduced | No | No | |
| Replacing a septic tank with package treatment plant (PTP) (Example 1) | No | No | |
| Changing property name/address | Yes | No | |
| Sewage treatment system is improving and the registration needs to be amended (Example 2) | Yes | No | |
| Moving discharge outfall location | Yes | Yes | £133 |
| Change to where the sewage effluent is discharging to (Soakaway to watercourse or vice versa) | Yes | Yes | £133 |
| Increase in the population equivalent (p.e.) (non-domestic) | Yes | Yes | £133 |
| Reduction in the type or standard of sewage treatment | Yes | Yes | £133 |
Application fee correct from 1 April 2025 until 31 October 2025
Example 1: A septic tank is being replaced by a package treatment plant (PTP). A registration has been granted for this “discharge of sewage effluent treated by a septic tank or to a standard that is better than that provided by a septic tank”. This registration does not require an amendment as a package treatment plant (PTP) treats effluent to a standard that is better than a septic tank.
Example 2: A registration has been granted for the “discharge of sewage effluent treated by a septic tank”. The septic tank is being replaced by a package treatment plant (PTP). The registration requires an amendment as sewage effluent will now be treated by a package treatment plant (PTP) and not a septic tank.
How to apply for a variation
To apply for a variation:
- Download the variation form.
- Complete the form with updated details.
- Email the form to the Water Permitting Team.
- Include payment if a fee applies.
Licence required
If you propose to increase the size of your discharge, so that it will be from more than 10 domestic properties or more than 50 p.e., you will need to apply for a licence. Contact water permitting.
If you wish to make a change in relation to a licence, contact water permitting to discuss with us.
What is population equivalent (p.e.)?
Population equivalent (p.e.) is a term that describes how much wastewater a single person will produce in a day.
If you're calculating the p.e. of a discharge from a mix of domestic and non-domestic properties, SEPA considers a single domestic property to be equivalent to five p.e. regardless of its size.