XY location data was acquired through a Freedom of Information (FOI) request under the Environmental Information Regulations (EIR) to Dŵr Cymru/Welsh Water.

You can find out more about storm sewer overflows and what Dŵr Cymru/Welsh Water is doing to monitor them on their website.

Permit numbers have been provided to allow users to cross reference with the Natural Resources Wales Public Register, which provides details of permit details as required under the Environmental Permit Regulations. You can access this permit information in the Consented Discharges to Controlled Waters with Conditions database on the LLe Geo-Portal for Wales. This includes data on the effluent type (e.g. Sewage effluent, Storm Overflow, Trade) and further detail is provided on the permit type and treatment type.

To create this layer, the Welsh EDM data was joined to the Welsh Consented Discharges Database in order to locate the unmonitored CSOs.