We are committed to providing accurate information about the performance of our sewer network as part of our approach to improving water quality in Scotland.
In our Improving Urban Waters Routemap, published in December 2021, we said we would increase reporting of discharge data from monitored overflows:
- By December 2022 publish annual data for monitored CSOs where data is already reported to SEPA, identifying the main reason for the spills where possible.
- By December 2023, publish discharge data annually for all other monitored CSOs.
- By December 2024, publish near real-time discharge data for all monitored CSOs.
What has been published?
We have now made available the historical data for reported overflow discharges covering the period 2018-2022.
This includes all reported overflows including CSOs, Settled Storm Sewage Overflows (SSSOs), and Emergency Overflows (EOs). However, it does not include reasons for discharges which Scottish Water does not currently record.
This data has been reported annually to SEPA as per license requirements and has previously been made available through relevant Freedom of Information requests.
Overflow Event Data
Download the Scottish Water Reported Overflow Event Data to SEPA 2018-2022 & Summary.Download here
Improving Urban Waters Routemap
Download the full routemap.Download here
Combined Sewer Overflow FAQs
Frequently asked questions about combined sewer overflows.View here
The information is available in searchable format by clicking on the blue box at the top of the page and selecting 'download'. This is supported by additional information, including metadata, user guidance, postcode, local authority area, and receiving water.
Please note that this data covers monitored and reported overflows only.
Reasons for discharges are not available for historic events reported to SEPA because Scottish Water was not required to collect or report this information. Scottish Water intends to develop approaches to help identify reasons for discharges and this will become part of future releases of information.
Some parts of the system are operated on our behalf by PFI operators. Where identified as the responsible person for the asset within the discharge license, these operators submit flow and event returns direct to SEPA.
Scottish Water will not publish information other operators report to SEPA. However, as PFI assets return to Scottish Water ownership at the conclusion of PFI contracts, we will then include discharge information from these in our future annual returns to SEPA and this will be subsequently published.
Any grid references within the data set relate to the asset location/monitoring point and not the receiving water.
Find out more about Scotland’s sewers and our improvement plans