This map shows the locations of large raised reservoirs in England and Wales, based on data extracted from the Environment Agency's public register as at 3 November 2025 and published from Natural Resources Wales's public register on 30 October 2025.
A large raised reservoir is a structure that holds 25,000 cubic metres or more of water above ground level. These reservoirs are regulated by the Environment Agency and Natural Resources Wales under the Reservoirs Act 1975 (as amended).
The information on this map is available as open data on my Datadaptive site, in CSV, KMZ and GeoJSON formats.
I originally compiled the data for England from a report that the EA released to me following a decision by the ICO. The EA has disclosed updated data extracts since then, most recently in early November 2025. The data for Wales is from a redacted extract published online by Natural Resources Wales at the end of October 2025.
Personal data has been redacted.