We’ve been asking our OS Champions and staff to share their favourite dog walks with us. Tracey Purnell has chosen Maerdy to Lluest Wen Reservoir as one of her and her dogs favourite walks. Starting from the village of Maerdy at the head of the Rhondda Fach, this walk explores the quiet uplands of the Rhondda Valley. The route climbs steadily above the valley floor to reach the remote Lluest Wen Reservoir, with wide views over the surrounding moorland and a strong sense of South Wales’ industrial and natural heritage.
Maerdy to Lluest Wen Reservoir – a great dog walk
The Maerdy to Lluest Wen walk is a particular favourite for my dogs, largely because of the amount of water along the route. The river winds gently alongside the path, offering plenty of opportunities for the occasional splash and play. Castell Nos Reservoir provides the perfect spot for Gwen to enjoy a paddle while Halle can take a proper swim. The quietness of the area is another real advantage — it’s often wonderfully peaceful, allowing the dogs to enjoy the freedom of the hills without the bustle of busy park paths. The mixture of forest tracks, open moorland and riverside sections keeps the walk engaging, with plenty of new scents and natural features for them to explore along the way.
Maerdy to Lluest Wen Reservoir Step by Step Guide
Where to park: Free parking is available at Maerdy Gateway Memorial Garden (CF43 4DD).
Duration: Approximately 2 hours 40 minutes
Terrain: Leisurely route on tarmac and well-maintained forestry gravel paths
OS Maps Link: Maerdy to Lluest Wen Reservoir
Follow the footpath down towards the river, where the route begins by tracing the riverbank through peaceful woodland surroundings.
As you continue, you will notice glimpses of the former colliery tramline, a reminder of the area’s industrial heritage. Shortly afterwards, the historic Castell Nos Filter House comes into view ahead.
Constructed between 1884 and 1900 as part of the Rhondda Fach water scheme, the Castell Nos Filter House played a significant role in supplying clean water to the valley communities. Above the filter house lie the remains of Castell Nos, a medieval Welsh castle dating back to around 1240. Although little of the structure survives today, its elevated position offers a sense of its former strategic importance. A circular blue plaque near the filter house, commemorate the location. The plaque was unveiled in 2009 by the Mayor of Rhondda Cynon Taf.
A short distance further along the path is Castell Nos Reservoir, where the landscape opens to reveal expansive views of the surrounding hills and forestry. At the base of the reservoir spillway, remnants of old colliery workings can still be seen, including the remains of a tramway bridge.
The route then continues towards Lluest Wen Reservoir. As the river narrows, the water gathers pace, creating a series of impressive waterfalls that provide a striking and memorable conclusion as you retrace your steps to this scenic valley walk.
You can follow more of Tracy’s adventures on her Instagram: @inspire_adventure_wales
