www.SewageMap.co.uk and POOPy: Open-source tools for understanding and communicating the environmental impacts of combined sewer overflows in real-time

Alex George Lipp , Jonathan Dawe, Sudhir Balaji

Combined Sewer Overflow (CSO) discharges occur when combined sewer systems exceed capacity leading to the discharge of untreated sewage and storm-water into rivers and seas. These events introduce pollutants such as microplastics, pharmaceuticals, and faecal matter into the environment, negatively impacting water-quality & ecosystems, as well as posing a risk to public health. In England, UK, rising public concern about CSOs has driven large infrastructure efforts and led to legislation requiring water companies to enhance monitoring through what is called Event Duration Monitoring (EDM). EDM tracks whether a CSO is discharging and for how long. Since 2020, EDM summary statistics have been published and widely discussed in the public domain. More recently, real-time EDM data has been provided by water and sewerage companies and visualised on maps by these companies and some non-governmental organizations. However, challenges remain: inconsistencies in EDM data sources create barriers for analysing these new public datasets. Moreover, current visualisations don't clearly link CSOs to their environmental impacts. These challenges are compounded by low overall public-trust in water companies. To address this, we developed the open-source python toolkit POOPy (Pollution Discharge Monitoring in Object Oriented Python) and the data-visualisation website www.SewageMap.co.uk. POOPy provides a standardised interface to EDM datasets from diverse sources and provides functionalities to link CSO spills to impacted rivers. We use POOPy as part of the data processing pipeline which feeds into www.SewageMap.co.uk. This website shows the current status of thousands of EDMs across the country as well as identifying river stretches that are downstream of recently active CSOs. This website receives thousands of views per month and is regularly used by citizen-scientists, recreational water users and academic scientists. Around 80\% of users access the application via mobile or tablet devices, emphasizing the need to prioritize mobile users when designing interfaces for environmental datasets. We argue that our workflow offers a scalable and transparent model for interpreting, processing and communicating live environmental data-streams to the public.