The Upper Sûre Lake, a drinking water reservoir you can swim in

The Upper Sûre Lake is the biggest stretch of water in Luxembourg, and the first thing to grasp is what it’s for. It isn’t a leisure lake that happens to supply water; it’s the country’s main drinking water reservoir, which also lets you swim in certain spots in certain months. Keep that in mind and the rules make sense and the day goes much better.

A dam and a drowned valley

visitluxembourg says work on the Esch-sur-Sûre dam began on 30 July 1955, launched by public works minister Bodson, to a design by the French engineer André Coyne, and that the concrete arch dam, with very little steel reinforcement, went up between 1955 and 1958. In 1959 the Sûre valley was flooded and four houses and farms disappeared under the water. The power station has run since 15 February 1960. The government’s portal dates the lake to 1961 and gives it 380 hectares; visitluxembourg says about 4 km² and more than 16 km long.

Upstream, the 23-metre Bavigne dam holds back logs and sand before they reach the reservoir. Today it’s a dive site with the submerged remains of the Loutschmillen mill, two small bridges and an old road.

The water half of Luxembourg drinks

About 70% of the population gets its drinking water from here, treated by SEBES since the late 1960s. That’s why there’s a protection zone from the main dam to about 5 km into the lake where no water sports are allowed, and why engines are banned on the whole lake. If algae worry you, the Water Management Authority is clear. Treatment removes the toxins and tap water carries no risk. For British visitors, it’s a bit like finding a Lake District reservoir that also has official swimming beaches.

Once your dates are set, check which hotels are still free in Esch-sur-Sûre before prices climb.

Where to swim

Officially, Luxembourg lets you swim from 1 May until 30 September, and the lake has six areas monitored by the Water Management Authority. Four are in the Esch-sur-Sûre commune, Lultzhausen and the three around Insenborn; Liefrange belongs to Lac de la Haute-Sûre, and the Rommwiss in Boulaide. In the 2025 assessment every one of them scored ‘excellent’. They’re grass lawns rather than sand, open from 7:00 to 23:00, and some are only reached after a few minutes’ walk.

The Upper Sûre’s weak spot is cyanobacteria. The authority itself says the lake is particularly vulnerable, and a bloom can close a zone even when the water is excellent. In the last days of the 2026 season swimming at the Rommwiss was banned. Swimming stopped on 30 September 2026 and won’t return before 1 May 2027, so until then the lake is for walking and paddling.

Paddling, diving and the solar boat

At Lultzhausen you can hire canoes, kayaks and stand-up paddleboards from the youth hostel or the water sports centre, which also runs lessons. Other bases around the country are in canoeing and kayaking in Luxembourg. With your own kit you can paddle outside the protected zone. Certified divers can dive at Lultzhausen all year, and the government portal mentions stations for filling tanks. The guided solar boat trip covers wildlife, plants and water protection; the amphibious version pairs it with an 8 km walk along the left bank. The jetty is on Insenborn beach.

Once your dates are set, check which hotels are still free in Esch-sur-Sûre before prices climb.

The rules, no surprises

Dogs aren’t allowed on the Burfelt, Fuussefeld, Frounbierg, Liefrange and Lultzhausen lawns. Barbecues are only allowed on the fixed grills at Fuussefeld and Lultzhausen, and in 2026, according to Visit Éislek and the Esch-sur-Sûre commune, a total fire ban was in force because of the drought. Music on headphones only, no wild camping and parking only in marked bays. In late September 2026 Visit Éislek was also warning of hornets at the Rommwiss.

Getting there and when to come

There’s no railway. At weekends and on bank holidays in season, bus lines 155 and 157 serve the lake stops, and in good weather a Plage-Bus links the Insenborn and Lultzhausen beaches with the car parks. If you drive, the Am Kéilert car park at Insenborn and the Kräizfeld at Lultzhausen are free and about 500 metres from the water.

For swimming, June to September. For walking the Circuit du Lac or climbing to the Belvédère Burfelt, any time of year. To compare with Echternach, Weiswampach or Remerschen, see my guide to swimming lakes in Luxembourg. For somewhere to sleep, Esch-sur-Sûre is the best bet.

If you would rather have a local show you round, book a guided tour in Upper Sûre Lake and choose by the reviews.

A car frees you from timetables: search car hire in Luxembourg on DiscoverCars and compare companies.

So you do not pay over the odds, look at trains, coaches and flights to Luxembourg on Omio and pick the one that suits you.