A large reservoir built to supply Cardiff with water. Authorised under Cardiff Corporation Act of 1884, (designated Reservoir No.1), the reservoir was built by direct labour, work commencing in1893 and was inaugurated on 30 September 1897. It was originally planned to hold 160 million gallons but capacity was increased to 345 million gallons by an Act of 1894; the top water level is at 1340ft. (408m) OD. The dam (SN98671815 -SN98951830) is at the southern end and is of a clay core dam faced in masonry, with a castellated valve tower at SN98881830. A temporary contractors village and workshops was erected to the S of dam site, on E bank of Taff Fawr between the Hirwaun and Merthyr roads (buildings formerly at Cantref Reservoir site). A contractors railway (standard gauge) was laid along the W bank of Taff Fawr from Cantref Reservoir in 1893, being dismantled in 1897.
D.J.Percival, RCAHMW, 09 August 2006.