Policy Brief: Addressing CSO spills

Sewage discharges from Combined Sewer Overflow (CSO) structures into receiving waters can prevent floods in urban areas but can also harm ecosystems and public health. In many countries there is a lack of reliable data on their operational frequency and pollution loads released. Assessing the impact of CSOs is challenging, emission-based rules that focus on the number of spills per year are insufficient to quantify environmental harm and lack of continuous information on the receiving water makes impact-based regulations hard to enforce. In this Policy in Brief we present the current status and some policy recomendations to address CSO spills.