The Bohernabreena Reservoir (Glenasmole Valley): A Lovely Dublin Ramble

The Bohernabreena Reservoir walk (in the Glenasmole Valley) is one of the more overlooked Dublin walks.

And it’s well worth doing, as you can pair it up with a visit to nearby Blessington in Wicklow (loads of walks here and places for a bit of lunch).

Although parking can be tricky, the scenery here is wonderful and, if you arrive early (emphasis on early) you’ll often have the place to yourself.

In the guide below, you’ll find info on everything from the Bohernabreena Reservoir walk to the history of the area.

Some quick need-to-knows about the Bohernabreena Reservoir

Although a visit to the Glenasmole Valley is fairly straightforward, there are a few need-to-knows that’ll make your visit that bit more enjoyable.

1. Location

The Bohernabreena Reservoir is about 15km southwest of Dublin. The Reservoir Park is in the Glenasmole Valley. It’s in a stunning area of natural beauty between the Wicklow National Park and the Dublin Mountains. It’s easy to reach off R114, 3.5km southwest of Tallaght. 

2. Opening hours

Access to the park is unlimited so there are no actual opening times. Just show up with your walking shoes and enjoy!

3. Parking 1 (only 15 spaces)

The original car park is very small and has just 15 spaces. If you want to park here, you’ll need to arrive early or visit at off-peak times. Avoid parking along the road here as it’s narrow and you’ll likely be towed.

4. New parking area (recommended)

There’s a new car park (see it here on maps) that costs €5 to park, but it’s secure, there’s toilets and they have a little spot selling coffee at the weekends, too. It’s also a short distance from an entry point for the loop walk here.

5. Part of Glenasmole Valley  

Glenasmole is an ancient landscape, caved out by glaciers during the last Ice Age. It consists of two valleys, the lower one being steeper and narrow. It’s a designated Area of Special Conservation with rare plants and wildlife. Wild orchids, molina meadows and petrifying springs are just some of the remarkable features. 

About the Bohernabreena Reservoir 

There are two reservoirs in the centre of Glenasmole Valley which are surrounded by evergreen and deciduous trees. The reservoirs are known collectively as the Bohernabreena Waterworks.

Managed by Dublin City Council, they are a significant source of Dublin’s water supply, providing drinking water for around 35,000 households in south Dublin city. 

The Liffey and Dodder combine

The River Liffey and the River Dodder rise in the nearby mountains and flow into the Bohernabreena Valley. Fed by several smaller brooks, the Dodder flows into the reservoir.

It provides pleasant riverside walks between the reservoir and the Dublin Mountains. Constructed between 1883 and 1887, the reservoirs stretch from Bohernabreena to Castlekelly.

Why it was built

They were created to provide water to the many mills in the area that lined the Dodder and its tributaries during the Industrial Revolution. They were also planned to create flood control in an area where flooding had been a problem for centuries.

The upper lake has clean drinking water collected from the non-peaty slopes. The lower lake contains more peaty water. The two are connected by a stone-lined channel which brings water directly from the upper to the lower lake.

It then flows to Ballyboden, 7.5km away, for treatment. There’s an impressive overflow system at the upper reservoir.

The Bohernabreena walk

Known as the Upper Reservoir Loop, the Bohernabreena Walk starts and ends at either of the Bohernabreena car parks (it’s a looped walk).

It’s an easy walk that takes 60-90 minutes covering 8.5km. It is signposted with orange way-markers which helps discern it from the yellow markers of the Dublin Mountains Way which also passes along part of the route.

The Upper Reservoir Loop runs along the road parallel to the River Dodder. It passes the lower reservoir and then continues along the same road to the upper lake. It follows a loop around the top of the reservoir along the wooded shoreline. Follow the loop trail back along the road to the car park.

Points of interest along the hike include the channel carrying water from the upper to the lower reservoir. On the eastern shore are the remains of St Ann’s Churchyard which was in use until the mid-16th century.

Things to do near the Bohernabreena Reservoir

One of the beauties of the Glenasmole Valley is that it’s a short spin away from some of the best things to do in Dublin.

Below, you’ll find a handful of things to see and do a stone’s throw from Bohernabreena Reservoir (plus places to eat and where to grab a post-adventure pint!).

1. Cruagh Wood (20-minute drive)   

Cruagh Wood is 3km east of Bohernabreena Reservoir Park, but it’s a winding 20 minute drive to reach it! There are several way-marked trails through Cruagh Wood including Dublin Mountains Way. The Slí na Sláinte loop forest road provides a very pleasant walk with access to Cruagh summit. At 522m elevation, it delivers stunning views of Dublin on a fine day. 

2. Blessington (25-minute drive)

South of Bohernabreena is the lovely lakeside town on the Blessington Lakes. This Dublin commuter village enjoys a rural lifestyle with a walker’s cafe and a chippie if you’re hungry. Hike around the lake or take the Blessington Greenway walk to Russborough House, one of Ireland’s finest stately homes filled with artworks. 

3. Ticknock (30-minute drive)

Head east from Bohernabreena along the M50 to tackle the Ticknock walk, another hike with superb views of Dublin Bay, the city and Wicklow. There’s a car park and a fairly flat forest road leading to Three Rocks Mountain. Continue on to Fairy Castle, an ancient passage tomb marking the highest point in the Dublin Mountains. 

FAQs about visiting Bohernabreena Reservoir in the Glenasmole Valley

We’ve had a lot of questions over the years asking about everything from ‘Where is Bohernabreena Reservoir?’ (it’s in Dublin) to ‘When was Bohernabreena reservoir built?’ (1883).

In the section below, we’ve popped in the most FAQs that we’ve received. If you have a question that we haven’t tackled, ask away in the comments section below.

How long is the Bohernabreena Reservoir walk?

The Bohernabreena Reservoir walk should take you no more than 60-90 minutes as you stroll along its 8.5km or so trail.

Is the parking at Bohernabreena really that bad?

There’s a very limited number of spaces. Arrive early and you’ll be fine. Avoid parking at the side of the road (see top of guide above for more info).