1. Home
  2. Topics
  3. Water

Back to Water

Septic tanks and Private Sewage Treatment Systems

Table of contents
Select a section to jump to:
Select a section to jump to:

If your property isn’t connected to the public sewer, you likely use a private sewage treatment system - such as a septic tank or package treatment plant. These systems treat wastewater from one or more properties and discharge it to land or water. If you can't connect to the public sewer, you must apply to SEPA for an authorisation to discharge.

When do you need to register your sewage discharge

You can apply to register your discharge if it is from:

  • up to 10 domestic properties; or
  • from a combination of domestic and non-domestic properties that serve a population equivalent (p.e.) of up to 50.

This is unless you are discharging to a phosphate sensitive catchment or to a freshwater lock. If you are discharging to these locations you will need a permit.

Types of discharges that need to be registered

  • Discharge from a treatment system that is less than 2 years old or not yet in use (for example, if you're still in the planning stage of building a house or business). We refer to a discharge from these systems as a new discharge.
  • Discharge from a treatment system that has been in use for more than 2 years. We refer to a discharge from these systems as an existing discharge.
  • Composting toilets, or no flush toilets. In the UK, most composting toilets separate out the liquid (urine). If you have a urine-diverting toilet, we refer to this as a discharge of liquid from a composting toilet.
  • Discharge of water from sinks, baths, showers and washing machines, not from a toilet, is known as grey water.

What if my discharge is already registered?

If you need to check if your discharge is already registered you can find information on how to do this on our Private sewage treatment system registration check webpage.

Discharge registered before 1st November 2025

Find out more information about if your discharge was authorised by a CAR registration on 31st October 2025.

Discharge authorised on or after 1st November 2025

If your discharge was registered on or after the 1st November 2025, your registration will be subject to standard conditions. You can find out more information and standard conditions on our Discharge of sewage effluent page.

How to register a discharge

Registering a new discharge

Please read our registration guidance before you register a discharge. New discharges must connect to the public sewer where possible. If you have a new sewage discharge, you should contact Scottish Waterfor more information about connecting to the public sewer.

You can apply to register online if your discharge is:

  • from up to 10 domestic properties; or
  • from a combination of domestic and non-domestic properties that serve a population equivalent (p.e.) of up to 50

What you will need

  • The address or location of each connected property
  • Contact name and email address
  • To know if the treatment system has been in use for more than 2 years
  • The type of treatment system
  • The discharge location (to land, water, or sea)
  • Soil percolation test results (for land discharges)
  • Population equivalent (for non-domestic use)

Our online application service will help you decide what type of treatment system you need. You must pay a registration fee when you apply for a registration. The registration fee for a small sewage discharge is £190.

Registering an existing discharge

You can apply to register online if your discharge is from nine properties or less.

If your existing discharge is from 10 properties, you can't apply online. You should apply for a registration by completing an application form and emailing it to our Registry Team.

What you will need

  • Address or location of each connected property
  • Contact name and email address
  • To confirm if the treatment system has been in use for more than 2 years
  • You must pay a registration fee when you apply for a registration. The registration fee for a small sewage discharge is £190

If your existing discharge is untreated, you should contact us by emailing the Water Permitting Team.

Register a small sewage discharge

Registering a discharge of liquid from a composting toilet or grey water

You don't need a discharge authorisation if your composting toilets has no urine separation because there is no discharge. However, these can be a problem in our climate as the waste doesn't always compost properly.

If your discharge is liquid from a composting toilet or grey water, you can't apply online. Our Discharge of grey water or of liquid from a composting toilet page provides further information on how to apply.

Properly composted solid waste and the urine from a composting toilet in a private household can be used as fertiliser in line with General Binding Rule 18. Read the Know the Rules Factsheet 8: Organic fertiliser application on the Farming and Water website to find out how to comply with this rule.

If you are unable to register using our online service

It's quicker and easier to register your sewage discharge online, if you are unable to you can still apply by completing one of the application forms listed below and emailing it to our Registry Team.

If our service told you that your registration could not be completed online, read our Private sewage treatment system registration guidance for information about what to do next.

After you register

After you register a small sewage discharge, you must meet the conditions of your registration. These can be found on our webpages. 

When you need to apply for a permit

For some sewage discharges you need to apply for a permit. You must apply for a permit to:

Maintaining your system

In order to comply with your conditions, you must properly maintain your private sewage treatment system. You should:

  • De-sludge annually
  • Follow manufacturer’s servicing instructions
  • Check soakaways and outfall pipes
  • Avoid flushing fats, oils, or non-biodegradable items

For shared systems, maintenance responsibilities are shared among connected properties. Read the Maintaining your private sewage treatment system guidance document.

Need help?