- Category: Water Feature
- Type: Inland Water
- Latitude/Longitude: 53°4'39"N 3°35'25"W
- Eastings/Northings: 293558, 354547
- OS Grid: SH935545
- Mapcode Local: GBR 6D.B4BN
- Mapcode Global: WH666.TXG3
Location and coordinates are for the approximate centre of Alwen Reservoir within this administrative area.
Geographic features and populated places may cross administrative borders.