Private sewage treatment system registration guidance
Read this guidance before starting any application. This guidance applies to the registration of discharges from private sewage treatment systems that are less than two years old.
Before you apply for a registration
Check if you can connect to the public sewer system
Where possible, sewage discharges must be connected to the public sewer system. Contact Scottish Water to determine how far away from the public sewer you are. If your new sewage discharge is near the public sewer, Scottish Water can give you more information about connecting.
In most cases, we will not authorise a sewage discharge if it is near the public sewer and we think it would be reasonable for you to connect to it. Our online registration service will carry out a check on how close your discharge is. Your application will not be accepted if the discharge is near the public sewer.
You can determine if you are near the public sewer by multiplying the number of domestic properties (or five population equivalents (p.e.) for non-domestic properties) by 30 metres. If the nearest of the properties is within this distance, the discharge is near the sewer.
Example one:
Three houses (domestic properties) are built 85 metres from the public sewer.
Calculate if the discharge is near the sewer:
= number of properties x 30m
= three properties x 30m
= 90m
The properties are less than 90 metres away so we would consider it near the public sewer.
Example two:
A small café (non-domestic property) with a population equivalent of 25 p.e. is built 100 metres from the public sewer.
Calculate if the discharge is near the sewer:
= (property p.e. divided by five p.e) x 30m
= (25 divided by five) x 30
= five x 30m
= 150m
The café is less than 150 metres away so we would consider it near the public sewer.
If you don't know what the population equivalent is for your non-domestic property, read our guidance in how to work out population equivalent for non-domestic properties.
There may be several reasons why connection to the sewer isn't possible. These include lack of capacity in the sewer or practical issues such as a major road or river between the property and the public sewer.
If you can't connect to the public sewer, you will need to register your discharge with SEPA.
We will only authorise sewage discharges near the public sewer where you can justify that connection isn't reasonably practical. Your justification should include a breakdown of estimated costs and proof of any discussions with Scottish Water.
You should apply for a registration by completing an application form and emailing it to our Registry Team.
Check your discharge is treated
An untreated discharge is a discharge that doesn't go through any type of treatment before it is discharged to land or water.
We will not authorise new untreated sewage discharges.
Check if you can apply for a registration for your discharge
For some small sewage discharges you need to apply for a licence instead of a registration. This is usually because of where you want to discharge to and the risk of harm to the water environment it could cause.
You can't apply for a registration if:
- Your discharge is in a phosphate sensitive catchment. This is an area at risk of significant nutrient enrichment, which can be caused by sewage discharges. These are the catchments of Loch Leven (Perth and Kinross), Lunan Lochs (Perth and Kinross) and Loch Flemington (Highland).
- You want to discharge directly into a freshwater loch or pond.
- Your discharge is from more than 10 domestic properties.
- Your discharge is from non-domestic properties or a combination of domestic and non-domestic properties that serve a population equivalent (p.e.) of more than 50.
If you need to apply for a licence for your discharge, you should read how to apply for a licence to discharge sewage effluent before you apply. We also recommend that you discuss your proposed discharge with us by emailing our Water Permitting Team.
To work out the population equivalent (p.e.) for a non-domestic property, you need to use the following calculation:
(maximum number of people who could use the system x BOD load) divided by 60 = p.e.
BOD load is the biochemical oxygen demand load for the type of property. You can find out what the BOD load is for different types of non-domestic properties in the British Water Code of Practice - Flows and Loads (table of loadings for sewage treatment systems).
The number you get from the calculation is then rounded up to the nearest whole number to give you the population equivalent.
Example:
A snack bar has 100 customers a day. The BOD load for this type of property is 19 grams per person per day.
=(maximum number of people who could use the system x BOD load) divided by 60
= (100 x 19) divided by 60
= 1,900 divided by 60
= 31.7
= 32 p.e. (rounded up figure)
If your discharge is from mix of domestic and non-domestic properties, we use a population equivalent of five p.e. for a single domestic property, regardless of size of the property.
Check if you can discharge to a soakaway
If you can't connect to the public sewer, you must check if the conditions are suitable for your treated sewage effluent to discharge to land via a soakaway. To do this, you will need to carry out a soil percolation test. This measures how long it takes your discharge to drain from the soakaway into the surrounding soil.
Information on soil percolation tests is available in the Scottish Government Building Standards Technical Handbook.
For more information on soakaways, read discharging to land via a soakaway.
Check if you need to apply for one or more than one registration
Some properties have their own treatment system but share a soakaway or an outfall pipe with other properties. In this case, you will need to apply for a registration for the discharge from each treatment system.
Apply for a registration
When you apply to register your sewage discharge, you will need to know where your treated sewage discharge point is and if this is to land via a soakaway or to water:
- Discharging to land via a soakaway.
- Discharging to a watercourse.
- Discharging to the sea or an estuary.