Sewage discharges occur when water companies release raw wastewater from combined sewer overflows (CSOs) into seas, rivers and other bodies of water. Our sewage map highlights CSOs across the UK, and will show you how many are active, and where they are. Confirmation of a sewage overflow operating, however, doesn’t always provide you with enough context to know when it is safe to enter the water. While discharges tell you where sewage overflows are and when they are in use, they do not indicate whether the discharge may affect water quality or pose a risk to human health.

In contrast, sewage alerts are issued specifically for designated bathing waters to inform water users when water quality is compromised, and it may be unsafe to enter the water. These alerts are formed using water companies’ data and impact modelling that provide risk assessments and create clear warnings. We send you a notification to let you know that a particular bathing water has been impacted by a nearby discharge. While discharges can trigger alerts, not every single discharge will do so, due to a variety of factors – such as the specific waterway’s proximity to a CSO or its bathing water status (or lack thereof).

Understanding these differences is important. It highlights why we need a national sewage alert system so that water users can know when locations are impacted, not just access to locations of sewage overflows and their status as this alone make it difficult to understand the risks.