5k Run Hirwaun: Scenic Llwyn-on Reservoir Loop Adventure

Route Overview & Local Insights

This 5km loop around Llwyn-on Reservoir offers a quintessential Brecon Beacons running experience with a gentle profile that makes it accessible for all abilities. Starting with a manageable 28m of ascent, the first half of the circuit takes you along forested trails that provide natural shelter and soft footing, while the return leg transitions onto a quiet, paved singletrack lane. Though the course is classified as hilly for its rolling landscape, the terrain is well-maintained and provides a consistent rhythm for runners looking to enjoy the stunning waterfront views and lush Welsh greenery without technical difficulty.

Set within the Taf Fawr valley, Llwyn-on is the largest of the three reservoirs in this part of the Brecon Beacons National Park. As you navigate the clockwise loop, you’re running through a landscape steeped in industrial heritage; the reservoir was completed in 1926 to supply water to the growing population of Cardiff. Local runners often favor this route for its microclimate—the surrounding woodlands of the Garw Nant provide a crisp, fresh atmospheric quality even on warmer days. After completing your loop, you are perfectly positioned near Hirwaun to explore the wider "Waterfall Country" or grab a post-run coffee in one of the traditional valley villages.