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Hiking trails & Routes
South Wales
Rhondda Cynon Taf
Hirwaun

Llwyn-onn Reservoir loop

Easy

4.4

(36)

295

hikers

Llwyn-onn Reservoir loop

01:26

5.43km

50m

Hiking

Embark on an easy hike around Llwyn-onn Reservoir, a 3.4-mile (5.4 km) loop that takes about 1 hour and 26 minutes to complete. You will gain a gentle 168 feet (51 metres) in elevation, making this a perfect relaxed outing. As you follow the path, you will enjoy expansive views of the reservoir's deep blue waters, framed by the rolling hills of Bannau Brycheiniog National Park. The route also leads you through tranquil mixed woodlands and a fresh conifer plantation. Keep an eye out for local wildlife, especially near the bird hide.

Planning your visit is straightforward, as the trail is conveniently located near the A470, a main access route into the National Park. Parking is generally available for hikers. For additional facilities, the nearby Garwnant Visitor Centre offers amenities like toilets and a cafe. This makes it easy to prepare for your hike or relax afterwards.

This route is considered a hidden gem, offering a peaceful experience away from more crowded areas in the Brecon Beacons. The varied scenery includes not only the reservoir itself but also opportunities to spot wildlife such as otters and various bird species. The presence of a bird hide further enhances your chances of observing the natural inhabitants of this serene landscape.

Last updated: April 23, 2026

Tips

Your route passes through a protected area

Please check local regulations for:

Bannau Brycheiniog National Park

Waypoints

A

Start point

Parking

Get Directions

1

121 m

Garwnant Visitor Centre

Highlight • Rest Area

Brecon Beacons visitor centre with plenty of parking, a children’s play area, cafe.

Tip by

2

1.86 km

Llwyn-on Reservoir

Highlight • Forest

Zoe has given out a lot of the history of the dam. Let's just add a bit of local information to say that this is a hidden gem of a reservoir. Though well known by locals, it is still an under-visited location. There are lovely walks to be had either around it or through the adjacent forests, there is a cafe and a roadside service van with refreshments on the way around; and the trails are great. The forest views, quaint foot bridges, and views out over the water make it a very scenic area.

Tip by

3

2.89 km

Llwyn-on Reservoir Dam

Highlight • Structure

Llwyn-on reservoir, built in 1926, covers 150 acres and is the largest of the three in the Taff Fawr Valleys area. Walking along the shore you can be immersed in the fresh smells of the conifer forest and lapping sounds of the deep blue water - an ideal habitat for otters, great crested grebes, goldeneye, goosander and coot.

Tip by

B

5.43 km

End point

Parking

Loading

Way Types & Surfaces

Way Types

2.22 km

1.48 km

1.15 km

474 m

< 100 m

Surfaces

2.16 km

1.52 km

1.10 km

460 m

158 m

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Elevation

Elevation

Nothing selected – click and drag below to see the stats for a specific part of the route.

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Weather

Powered by Foreca

Tuesday 7 July

28°C

12°C

0 %

Additional weather tips

Max wind speed: 9.0 km/h

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Frequently Asked Questions

Where can I park for the Llwyn-onn Reservoir loop?

Parking is available near the trailhead. The trail is conveniently located near the A470, the main access route into Bannau Brycheiniog National Park. The nearby Garwnant Visitor Centre also offers parking and is a good starting point.

Is the Llwyn-onn Reservoir loop dog-friendly?

Yes, the Llwyn-onn Reservoir loop is generally dog-friendly. However, please ensure your dog is kept under control, preferably on a leash, especially around wildlife and other hikers. Always clean up after your pet to help keep the trail enjoyable for everyone.

What is the best time of year to hike the Llwyn-onn Reservoir loop?

The Llwyn-onn Reservoir loop can be enjoyed year-round. Spring and autumn offer pleasant temperatures and beautiful scenery with changing foliage. Summer is popular for its longer daylight hours, while winter can provide a tranquil, crisp experience, though some sections might be muddy, especially after rain.

Do I need a permit or pay an entrance fee for this trail or Bannau Brycheiniog National Park?

No, you do not need a permit or to pay an entrance fee to hike the Llwyn-onn Reservoir loop or to enter Bannau Brycheiniog National Park itself. Access to the park and its trails is generally free.

What is the terrain like on the Llwyn-onn Reservoir loop?

The trail features a mix of flat and gently inclined sections, making it largely accessible. You'll encounter hard, compacted surfaces, some looser sections, and both paved and unpaved areas. Be aware that some parts, particularly after crossing a weir, may become muddy, especially after wet weather.

How long does it take to complete the Llwyn-onn Reservoir loop?

The Llwyn-onn Reservoir loop is approximately 5.4 kilometers (3.4 miles) long and typically takes around 1 hour and 26 minutes to complete at a moderate hiking pace.

What can I see along the Llwyn-onn Reservoir loop?

Along the route, you'll enjoy expansive views of the deep blue waters of Llwyn-on Reservoir, framed by the rolling hills of the Brecon Beacons. The trail passes through mixed woodlands and a tranquil conifer plantation. You'll also encounter quaint footbridges, the impressive Llwyn-on Reservoir Dam, and potentially the ancient Pont ar Daf bridge if water levels are low. Environmental sculptures can also be found on the Wern and Willow walks.

What kind of wildlife can I expect to see on the trail?

The area is rich in wildlife. Keep an eye out for otters, great crested grebes, goldeneye ducks, goosanders, and coots. There's even a bird hide along the trail, offering excellent opportunities for spotting these species.

Is the Llwyn-onn Reservoir loop suitable for families with children?

Yes, the Llwyn-onn Reservoir loop is considered an easy and accessible walk, making it very suitable for families with children. Its gentle gradients and varied scenery provide an enjoyable outdoor experience for most ages and fitness levels.

Are there facilities available near the Llwyn-onn Reservoir loop?

Yes, the Garwnant Visitor Centre is conveniently located nearby. It offers essential facilities such as toilets and a cafe, making it a great place to start or finish your hike.

Does the Llwyn-onn Reservoir loop connect with other trails?

Yes, the Llwyn-onn Reservoir loop connects to and shares sections with the Taff Trail, a well-known long-distance route. This offers opportunities to extend your hike if you wish to explore further.

What makes the Llwyn-onn Reservoir loop a unique hiking experience?

Often considered a 'hidden gem' and an 'under-visited location' by locals, this loop offers a peaceful experience away from more crowded trails. Its blend of reservoir views, tranquil woodlands, and the occasional glimpse of historical features like the Pont ar Daf bridge (when water levels are low) provides a distinctive and serene outing in Bannau Brycheiniog National Park.

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