Former filter beds on Afon Sawdde below Llyn y Fan Fach Reservoir, including weirs is a Grade II listed building in the Brecon Beacons National Park local planning authority area, Wales. First listed on 16 February 2022. Filter beds.
Former filter beds on Afon Sawdde below Llyn y Fan Fach Reservoir, including weirs
- WRENN ID
- over-lead-nightshade
- Grade
- II
- Local Planning Authority
- Brecon Beacons National Park
- Constituency
- Caerfyrddin MP: Ann Davies (PC)
- Country
- Wales
- Date first listed
- 16 February 2022
- Type
- Filter beds
- Address
- Former filter beds on Afon Sawdde below Llyn y Fan Fach Reservoir, including weirs, Llanddeusant, Carmarthenshire
- OS grid reference
- SN 803 230
- Coordinates
- 51.89284, -3.74088
- Source
- Cadw listing
Description
The former filter beds on the Afon Sawdde, located below the Llyn y Fan Fach Reservoir, date back to a time when they were used for water filtration. The Afon Sawdde flows into the filter beds through a shallow stone arch on the southern side. There are two filter beds, featuring concrete side walls on either side of a central channel. On the downstream side, there is a dam wall constructed from quarried rock-faced stone for the outer beds, while the central weir is made of smoother dressed stone.
On the upstream side, there are three weirs made of stone and concrete. Additionally, there is a rubble-stone parapet along the eastern side of the track, which includes openings with slots for stop planks.
Local climate
Former filter beds on Afon Sawdde below Llyn y Fan Fach Reservoir, including weirs sits in one of the wettest parts of the UK, with an average of 1,460 mm of rain a year. This makes it wetter than 98% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 92% of listed buildings.
It experiences an average of 53 freeze-thaw cycles a year, more than 93% 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
- No related consent applications matched
- 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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