[1] The 110 ft high embankment has, since its completion in 1927, been holding back 15,400 megalitres of water for supply to industry and population to the south.

At maximum fill level, the modern reservoir is continuous with Pentwyn Reservoir (sometimes referred to as Dol-y-gaer Reservoir or Lake) which suffered major water losses after completion due to the presence of major fractures in the bedrock beneath its dam relating to the Neath Disturbance, a major geological fault which runs northeast to southwest through the area.

The Taff Trail runs through the woods on the western side of the reservoir whilst Merthyr Tydfil sailing club is based on the eastern bank.

Most of the banks of the reservoir have been heavily afforested by Welsh Water though management of these woods is undertaken by Natural Resources Wales on behalf of the company.

The Reservoir's bell-mouth spillway (also known as plug hole) featured prominently in the opening scenes of the BBC’s 2021 television drama entitled The Pact, as well as in the final episode of the series.