- Category: Water Feature
- Type: Inland Water
- Latitude/Longitude: 51°31'44"N 3°10'22"W
- Eastings/Northings: 318725, 181785
- OS Grid: ST187817
- Mapcode Local: GBR KK1.GT
- Mapcode Global: VH6F0.YTDN
Location and coordinates are for the approximate centre of Llanishen Reservoir within this administrative area.
Geographic features and populated places may cross administrative borders.