Compensation Basin at Pontsticill Water Treatment Works is a Grade II listed building in the Brecon Beacons National Park local planning authority area, Wales. First listed on 19 May 1999. Water treatment works. 1 related planning application.

Compensation Basin at Pontsticill Water Treatment Works

WRENN ID
watchful-minaret-gold
Grade
II
Local Planning Authority
Brecon Beacons National Park
Constituency
Merthyr Tydfil and Aberdare MP: Gerald Jones (Lab)
Country
Wales
Date first listed
19 May 1999
Type
Water treatment works
Address
Compensation Basin at Pontsticill Water Treatment Works, Vaynor, Merthyr Tydfil, CF48 2UP
OS grid reference
SO 060 117
Coordinates
51.79625, -3.36377
Source
Cadw listing

Also on this page: related consents · flood risk · radon risk · weather exposure · detailed attributes ↓

Description

The Compensation Basin at Pontsticill Water Treatment Works is a notable structure that includes the portal of a tunnel, the walls, piers, and steps of a curved basin, as well as a weir. The tunnel is lined with brick, while the portal features large blocks of coursed rock-faced stone, massive granite voussoirs with diamond ends, a keystone, and a frieze of dentil moulding. Flanking piers rise to a cornice made of giant blocks, which contains a pedimented surround for a bronze plaque. On either side, walls of coursed rock-faced stone border the basin, and flights of steps with giant rock-faced coping lead down to the water level in front of the portal. The weir, which includes four sluices with piers on each side, marks the end of the basin and the return to the river.

Local climate

Compensation Basin at Pontsticill Water Treatment Works sits in one of the wettest parts of the UK, with an average of 1,270 mm of rain a year. This makes it wetter than 94% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 85% of listed buildings.

It experiences an average of 54 freeze-thaw cycles a year, more than 94% of listed buildings. Of these, 30 follow at least 1 mm of rain in the preceding 48 hours. Average temperatures at this location have risen by 0.3°C per decade since 1991.

Averages for 1991–2020; temperature trend 1991–2025. Figures describe the wider area (a grid cell of roughly 10 km), not the individual site. Contains modified Copernicus Climate Change Service information 2026.

More on this building

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  • No EPC on record for this property
  • No sale records on file
  • Related listed building consents — 1 application
  • Detailed attributes — period, style, materials, features
  • Flood risk assessment
  • Radon risk assessment
  • Weather exposure and heating demand — rain and frost month by month and year by year, wind direction, solar and humidity
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Nearby listed buildings

  1. Turbine House at Pontsticill Water Treatment Works Grade II 16 m
  2. Filter House at Pontsticill Water Treatment Works Grade II 85 m
  3. Dam, valve tower, bridge and outflow on Pontsticill Reservoir Grade II 186 m
  4. Dam, valve tower, bridge and outflow on Pontsticill Reservoir Grade II 228 m
  5. Pont Sticill (also known as Pontsticill Bridge) Grade II 282 m
  6. Pont Sticill (also known as Pontsticill Bridge) Grade II 286 m
  7. Brecon and Merthyr Railway bridge beside Ponsticill Reservoir Grade II 649 m
  8. Fingerpost near Church of St Gwynno Grade II 1.6 km
  9. Gravestone of Robert Thompson Crawshay and surrounding railings Grade II 1.8 km
  10. Tower of Old Church of St Gwynno Grade II 1.9 km