State of Luxembourg's water supply

To enjoy clean water in Luxembourg, all you have to do is turn on the tap. You don't even have to think of where it comes from or disappears to in the drain. But is there enough water to meet the growing demand of the Grand Duchy? What about water quality? How is this subject trated in the country?

A growing and diverse demand  

According to the government, regular use of water has doubled in Luxembourg over the last 15 years. On average, 130,000 m3 cubic meters of water are withdrawn each day, corresponding to around 180 litres per capita. According to a study conducted by the Administration de la gestion de l’eau (AGE), households account for about 60% of national water consumption. Although drinking tap water represents a very small amount of the total volume used by households, this habit is gaining traction among the Luxembourg population. A survey on the general perception on tap water consumption in Luxembourg was carried out by TNS Ilres in August 2020. 82% of residents reported drinking tap water, 58% of them every day (compared to 40% and 28% in 2006). The reasons mentioned were that it is more ecological (78%), less expensive (59%), more convenient (51%) and that they consider tap water to be of good quality (47%). 94% of respondents agreed that water is a precious and limited resource that must be protected.

Beside households, 23% of water volumes are used in the industrial sector and 8% by the agricultural sector. The remaining 9% represent water that is unaccounted for, for example through leaks. It is worth mentioning that construction (industry sector) also has a high consumption rate, which is proven each year by the "congé collectif" when daily water consumption drops by 10,000 m3. Luckily this break occurs in the summer, when Luxembourg faces its peak risk of water shortages.

The overall trend is one of increasing demand for water in the country, particularly in relation to the growing population and its associated needs. A study conducted by the University of Luxembourg lead by Ass. Professor Dr. Ariane König included the participatory development of three scenarios for 2045.  One aspect included the quantitative modelling of water demand and supply under diverse conditions in the future: At the current growth rates (with an increase of 12,500 people per year), and without water saving measures, it is likely that water availability will be a limiting factor for population growth after 2023-2029. In addition, the report highlights that likely changes in seasonal weather patterns due to climate change can potentially severely destabilise the seasonal water supply, especially during peak demand times in summer.

How can the country respond to that growing water demand? As of today, around 45% comes from municipal springs (ground water), and 55 % from the Esch-sur-Sûre reservoir (surface water). Because surface water contains germs and micro-organisms, it must go through complex treatment processes before it is safe for drinking. In Luxembourg this is done by the Syndicat des eaux du barrage d'Esch-sur-Sûre (SEBES) which currently has a capacity of between 70,000 to 110,000 m3 per day. Whenever demand for drinking water exceeds this capacity, the SEBES tops up its production with groundwater. Nevertheless, groundwater must be tapped in a way that it does not enter into contact with surface water, which is why such water must be pumped from boreholes or spring-boxes. Luxembourg has
a total of 250 groundwater resources.

While the country is able to cover current needs, it must prepare for the various challenges facing water in Luxembourg.

Disruptions to the natural cycle of water

Due to climate change, extreme weathers are an increasing reality for Luxembourg, as elesewhere. The 2016 and 2021 extreme flooding events in the months of May-July indicate changing weather patterns.
A reported 105,8 mm of rain fell on the 14th of July 2021, a new national record since documentation began in 1854, triggering devastating floods throughout the country. The Sauer River level reached 975 cm on the 15th of July 2021, with a current crisis alert level at 300 cm. Extreme rainfall over a short time period does not infiltrate into the ground in the same way as the same amount of rain distributed over longer period of time, says Ariane König. The resulting run-off can trigger flooding and landslides. Quicker run-off into rivers also means that there is less replenishment of ground water reservoirs, and in settlements, additional large amounts of run-off can present challenges in water treatment plants.

Reviewed urban infrastructures and green spaces that include water collection basins to optimise local storage and infiltration are important, as are river renaturation projects and the planting of tree lines as buffers along rivers and streams.

Surprisingly, July can turn out to be a month of heavy rains or droughts... Lack of water is indeed another issue that Luxembourg is and will increasingly be facing. Especially during the peak period of July, typically the warmest and driest month in Luxembourg, droughts and excessive use of water from citizens often lead to water scarcity. Furthermore, while droughts are typically associated with high temperatures during summer months, greater parts of Europe, including Luxembourg, witnessed a winter drought this year. This receives little attention in the country but poses significant challenges to the water reserves.

The pollution challenge

Luxembourg's water resources are vulnerable to pollution from human activities. The most widespread pressures on waterbodies stem from nitrates, presticides and phosphates from households and agriculture. This leads to polluted groundwater sources which puts pressure on our water reserves as well as biodiversity and soil quality. Out of Luxembourg’s 250 groundwater resources, around 100 cannot currently be used due to pollution concerns.

Under the EU Water Framework Directive, member states should achieve good natural quality for their waters by 2027. In Luxembourg, only around 2% of surface water bodies and 50% of its groundwater bodies meet this target, mostly due to pollution from agriculture and the effects of urbanisation.

Time to rethink our water use

Jeannot Schroeder from +ImpaKT, expert in circular economy and working with the AGE on water management, argues that our relationship with water starts with the problematic language we use: "We don’t consume water, he stresses, we use and pollute water." Water consumption is only the portion of water stocked in a product and thus no longer available for reuse. Most purposes for which we require water, such as hydrating our bodies, flushing the toilet, or cooling servers, use far more water than they consume. "Even when we drink water, the majority leaves our body again, only now it is polluted," he explains. The real issue is therefore not our water consumption, but the degree to which we pollute it. Rethinking the way we use water, next to reducing it, is thus crucial.

Furthermore, Jeannot Schroeder points out that our current approach to water is problematic: "Our linear economy currently takes the most efficient (economic) infrastructure solution to make the same high-quality water available for all applications," he says, "but, is it necessary to flush our toilets with the same water we drink?" For example, local reuse of water from the showers in toilets after reconditioning should become the new standard. In general, overall smarter reuse cycles to optimise water use are a necessity in the future, even if this will lead to higher costs in the beginning. A model which +ImpaKT champions is the "cascade model", where the quality of water, which decreases with each use, is aligned with the right purpose, in turn significantly reducing the amount of water we use. However, during the cascade use, water should not be contaminated with hazardous substances that cannot be removed.

Priority should therefore be given to a rethought approach to water and the AGE is exploring new ways of raising awareness and encouraging water sobriety. For example, the installation of water smart meters in homes is currently being tested by some municipalities. The feasibility of a potential structuring of the price of water is currently analyzed: to move from a price of water per m³ to a progressive price or a price based on usage... Because it is high time to realise that in Luxembourg, too, water is a precious resource. 

To be read also in the dossier "The Blue Gold Crisis"

• An endangered ressource
• Water is not a given
• Interview with About Amani
• Drawing for companies in action