ESS welcomes action in response to Storm Overflows Report

News Release

Immediate Release

5 November 2025

Environmental Standards Scotland welcomes action in response to its recommendation to identify instances where storm overflows spill in dry weather

Environmental Standards Scotland (ESS) has written to Scottish Water and the Scottish Environment Protection Agency (SEPA) to welcome their commitment to work together to develop a new analytical tool to identify instances where overflows in Scotland may be spilling in dry weather. This action has taken place in response to a recommendation made by ESS.

In 2024, ESS released an analytical report, Storm Overflows: as assessment of spills their impact on the water environment and the effectiveness of legislation and policy.

One of the report’s conclusions was that storm overflows in Scotland are at risk of spilling during dry weather – which should not happen. ESS went on to conclude that Scottish Water and SEPA may not have identified all the storm overflows that appear to spill in dry weather.

For example, Scottish Water and SEPA had identified 12 storm overflows in Scotland which are at risk of operating in dry weather. However, ESS’ analysis suggested that this is an underestimate.

At the time, ESS recommended that Scottish Water and SEPA should more routinely assess available rainfall, flow and spill event data to identify overflows which appear to spill in dry weather and prioritise these for investigation and improvement as soon as possible.

In response, Scottish Water and SEPA have now confirmed they are working to develop a new analytical tool to better understand the relationship between rainfall and spill data and to help them identify overflows where action is needed to prevent dry weather spills from happening.

Mark Roberts, Chief Executive of ESS said:

“Dry weather spills from storm overflows should not happen. These spills may have a greater environmental impact as the discharges will not be diluted by rainfall.

“It is encouraging that Scottish Water and SEPA have taken on board our recommendation and are acting to identify instances of dry spills and prioritise these for investigation and improvement.

“There is a high level of public concern on the operation and management of storm overflows in Scotland. It is important that commitments made by Scottish Water and SEPA in response to our report are delivered as soon as possible. ESS will continue to monitor progress as this new analytical tool is developed.”

Notes to editors

1. Read the ESS correspondence to Scottish Water and SEPA welcoming their commitment to work together to develop a new analytical tool to identify instances where overflows in Scotland may be spilling in dry weather.
2. Read the correspondence from Scottish Water and SEPA to ESS confirming the development of a new analytical tool to identify instances where overflows in Scotland may be spilling in dry weather.