Vartry Reservoir (Irish: Taiscumar Fheartraí) sits in the foothills of the Wicklow Mountains, just outside the village of Roundwood, roughly 50 km south of Dublin. Operated by Irish Water, this twin-lake system quietly performs a vital public service: storing and filtering fresh water that travels through a network of pipes to a service reservoir in Stillorgan, supplying the capital. For visitors, the site is a peaceful, traffic-light haven where 19th-century civil engineering meets accessible woodland trails, mountain views, and quiet waters.
A 19th-Century Public Health Marvel
The reservoirs were born from a sanitation crisis. By the mid-1800s, Dublin’s reliance on polluted canal water had led to recurring outbreaks of cholera and typhus. The Dublin Waterworks Act of 1861 authorised the damming of the River Vartry, and construction on the lower reservoir began under the supervision of the Dublin Water Works Committee, chaired by Dr John Gray. The lower dam was formally opened on 30 June 1863, delivering the city’s first reliable supply of clean, filtered water and dramatically improving urban public health.
As Dublin’s population grew, demand outstripped the original capacity. A second embankment, 3.5 km upstream, was completed in 1923 to form the upper reservoir. Together, the two lakes hold 16.9 billion litres of water. The lower reservoir reaches a maximum depth of 18.3 m, while the upper holds 5.6 billion litres at 13.4 m deep. The engineering works were considered remarkable for their time, featuring a controlled spillway that channels water between the lakes before it heads to the filter beds. The scheme even earned a literary nod in chapter 17 of James Joyce’s Ulysses, where the lower reservoir’s capacity is referenced in passing.
The Walking Trails
Three officially way-marked loops cater to different paces and interests. All are graded easy, well-maintained, and suitable for families, casual walkers, and dog owners.
| Trail | Distance | Way-marker | Approx. time | Start point |
|---|---|---|---|---|
| Lower Vartry Trail | 7.2 km | Blue | 2 hours | Roundwood village T-junction (R755/R765) |
| Upper Vartry Trail | 6.4 km | Green | 1.5 hours | Knockraheen entrance, east side of upper lake |
| Woodland Trail | 3 km | Pink | 45 minutes | Knockraheen entrance |
Lower Vartry Trail follows a traffic-free loop around the lower lake, skirting the shoreline on compact paths and quiet country roads. Keep an eye out for a hollowed-out Ballaun stone near the water’s edge, likely relocated from a nearby monastic site. When summer water levels drop, the stonework of the original bridge that once crossed the River Vartry reappears just beneath the surface.
Upper Vartry Trail climbs gently around the higher lake, offering clearer sightlines to the Sugar Loaf and Djouce ranges. The route includes a few short, steeper banked sections, but the overall gradient remains manageable. The trail is fully way-marked in green and passes through open pasture before dipping into mixed woodland.
Woodland Trail is a short, shaded circuit through a stand of century-old Scots Pines that separate the two reservoirs. The path follows a steep-sided cutting and provides a cool, quiet alternative on warmer days. It’s particularly popular with birdwatchers in spring and early summer.
Wildlife & Nature
The reservoir catchment is protected for its water quality, and the surrounding plantations create stable habitats for a range of species. The open water attracts grebes, which build distinctive floating nests anchored to reeds and lily pads. Mute swans, little egrets, grey herons, and black-headed gulls are regular visitors, while the pine edges and clear-felled glades support red squirrels, foxes, and occasional sika deer. Spring brings a chorus of songbirds to the canopy, and the reed beds along the lower shoreline provide cover for otters and water voles.
Practical Information
Vartry Reservoir is freely accessible year-round with no admission charge or formal opening hours. The site is managed by Irish Water, but there is no visitor centre on site.
Parking & Facilities
- Upper Vartry Car Park – Located at the Knockraheen entrance. Free parking with basic signage and public toilets.
- Lower Vartry Car Park – Situated near the trailhead in Roundwood village. Free parking with access to village amenities. Both areas are dog-friendly. Leashes are recommended near livestock and water edges.
Accessibility The Lower Vartry Trail is largely flat and suitable for strollers, though sections are gravel or compact earth. The Upper and Woodland trails feature moderate inclines and uneven ground. Detailed trail maps are available via Sport Ireland’s walking portal.
Getting There By car, take the M50 to the N11 southbound, exit at Kilmacanogue, and follow the R755 to Roundwood. The journey from Dublin takes approximately one hour. Public transport options include Bus Éireann routes 181 and 183, which stop in Roundwood village. From the bus stop, it’s a short walk to the Lower Trail start, or a quick taxi ride to the Knockraheen car park for the Upper and Woodland routes.
Nearby Attractions
Roundwood village is a two-minute drive from the trailheads and offers cafés, pubs, and convenience stores. The Sugar Mountain Café and Bistro serves specialty coffee and light meals, while An Tohar House is a reliable spot for a post-walk pint and traditional food.
For drivers, the Sally Gap circular route begins just west of Roundwood and winds through the Wicklow Mountains National Park, passing Lough Tay, Ballinastoe Woods, and Glenmacnass Waterfall. Mountain bikers can head to the nearby Ballinastoe MBT centre, which offers purpose-built trails through the same forested landscape. If you’re extending your day, Bray and Wicklow town are both within a 20-minute drive and offer coastal walks, historic architecture, and additional dining options.
Check water levels before visiting if you want to see the submerged bridge on the Lower Trail; late summer and early autumn typically offer the best visibility. Bring a waterproof layer and sturdy shoes, as the pine trails can stay damp well into the day.