The people of Luxembourg need not worry about running out of water

Whilst the drought in Luxembourg is having an increasingly noticeable impact on the country’s waterways, the drinking water supply remains stable for the time being. The Esch-sur-Sûre reservoir is at a high level, although some rivers and streams are showing alarmingly low levels.

According to Marc Hans, Director of the Water Management Agency, the situation regarding the supply of drinking water improved slightly in late July and early August. This is because the summer holidays and the period of collective leave in the construction sector have reduced overall consumption: schools are closed, many residents are abroad, and activity on building sites is minimal. However, Marc Hans warns that this respite may prove to be temporary. Once the holiday season is over, water consumption traditionally rises, and if regular rainfall does not resume by then, the situation could worsen.

Drinking water in Luxembourg is sourced from both surface and groundwater sources. A significant proportion of surface water is drawn from the Esch-sur-Sûre reservoir and treated by the Esch-sur-Sûre Dam Water Supply Syndicate (SEBES). Overall, around 60 per cent of drinking water comes from surface water, and 40 per cent from groundwater. Heavy rainfall last winter and in early spring helped to replenish groundwater reserves, although the capacity of some sources is now running low. At present, the water level in the Esch-sur-Sûre reservoir stands at around 316.5 metres above sea level, corresponding to approximately 42 million cubic metres. This is almost four metres higher than the lowest level on record, recorded in 2011.

Christian Schroeder, Deputy Director of SEBES, notes that the reservoir is at a very comfortable level for this time of year. Rainfall in March and April, as well as heavy rain further upstream in Belgium, allowed the water level to reach 319.5 metres – which is effectively the maximum – and to build up reserves ahead of the summer. The water level is currently falling by around six centimetres a day. This is due to drinking water production and the need to maintain a minimum flow downstream of the dam. August is usually a quieter month for the plant, which typically produces 60,000 cubic metres of drinking water per day. However, production has now risen to 75,000 cubic metres. The facility’s maximum capacity is 110,000 cubic metres per day, and additional groundwater sources can be utilised if necessary.

The situation remains far more critical for rivers and streams, particularly in the northern part of Luxembourg, which are suffering from a lack of rainfall. In some places, water levels are even lower than those recorded at the height of the 2022 drought. Falling water levels lead to higher water temperatures and lower oxygen levels, whilst pollutants become less diluted. Such conditions pose a serious threat to fish, insects and other aquatic organisms, and if sections of rivers dry up completely, the migration routes of these species are blocked.

A period of regular rainfall would help to rapidly improve the condition of the rivers, but it takes longer for groundwater reserves to recover. The soil must be thoroughly moistened before water begins to seep into deeper aquifers, and this process can take up to two months. Consequently, short-lived downpours are insufficient; sustained and steady rainfall is required.

If the dry weather continues until autumn, the starting conditions for next summer could deteriorate significantly. In the long term, the Water Management Agency is focusing on three main areas: reducing consumption, strengthening the protection of groundwater and developing new resources. One potential new source is the River Moselle, the water from which could be treated and used for drinking purposes in the future.

At present, the country remains in the national alert phase. In the event of a local deterioration in conditions, local authorities are entitled to restrict non-essential water use through local regulations; however, a ‘red alert’ phase with nationwide restrictions has not yet been declared in Luxembourg.