Frankley Reservoir is a semi-circular reservoir for drinking water in Birmingham, England, operated by Severn Trent Water. Its construction was authorised by the Birmingham Corporation Water Act 1892 (55 & 56 Vict. c. clxxiii) It was built by Birmingham Corporation Water Department to designs by Abram Kellett of Ealing in 1904. It contains 900000 m3 of water received from the Elan Valley Reservoirs, 117 km away, in Wales, which arrives via the Elan aqueduct, by the power of gravity alone, dropping 52 m – an average gradient of 1 in 2,300. Before 1987 it was leaking 540 L per second. In that year ground-penetrating radar was used successfully to isolate the leaks.