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Checking the water quality in your home

Enter your address to view the test results for drinking water quality in your area

Test results for drinking water quality

Drinking water is the most strictly regulated and stringently tested foodstuff in the European Union. Its quality is continuously monitored to guarantee its safety for human consumption, and it must comply with very strict standards set forth in the Grand Ducal Regulation of 7 October 2002 on the quality of water intended for human consumption, which itself is based on a European directive.

Testing of drinking water quality

The water supply is regularly tested for chemicals and bacteria both at the source and across the distribution network, and its quality meets the standards provided for by law.

The number of analyses performed is determined based on the volume distributed or produced each day within a distribution zone. These include, in particular:

routine testing, which is conducted monthly and analyses of a total of 26 parameters;

complete testing, which is conducted two to three times per year and analyses of a total of 106 parameters, including 49 different pesticides;

self-monitoring of springs and reservoirs, which is conducted regularly and includes two sets of complete tests per year, chemical analyses of samples, and weekly tests.

The Service Eaux (Water Department) conducts a total of over 2,000 tests per year.

Procedure for weekly analyses


Microbiological quality

The water's microbiological quality is assessed by regularly screening for waterborne bacteria that could contaminate consumers' supply.


Water hardness is determined by the amount of calcium and magnesium salts naturally present in the water. It is expressed in degrees, and varies between 0° and 50°.


Nitrates occur naturally in the ground and in the water supply. Excessive or poorly managed nitrate content in fertilisers leads to a build-up of nitrates in natural resources. To be considered safe for consumption by pregnant women and infants, water must not contain more than 50 mg of nitrates per litre.


The presence of pesticides in natural resources is caused by poor management of products used to protect crops or to kill weeds. Certain pesticides have or may have effects on human health when absorbed throughout a lifetime. The regulatory maximum of 0.1 mg/litre is lower than known toxicity thresholds.


Fluoride is a trace element that is naturally present in water. Moderate doses are beneficial to human health. A maximum regulatory limit of 1.5 mg/litre has been set to take account of the risks of dental fluorosis (staining of dental enamel). Public drinking water has an average fluoride content of 0.083 mg/litre: fluoride supplementation may be recommended, on medical advice.



To prevent the introduction of particulates that may promote pitting corrosion in pipes, we recommend installing a strainer-type filter – preferably self-cleaning (porosity of 100 microns) – at the point where the pipe enters the building. This device must be regularly checked and cleaned.


Where water has remained still for more than eight hours, the lead content in old pipes and/or internal networks may leach into the water. For this reason, if you are away from home for an extended period, we recommend that you let your taps run for a while before using the water.


Iron is not dangerous to human health, but its presence in water can be a nuisance, in particular when washing textiles. If you notice that your water has an unusual colour or taste, you should inform your supplier.

Cold-water systems

Generally, cold water distributed by Luxembourg City requires no treatment.

Hot water systems

Whether or not treatment is required depends primarily on the temperature of use and the type of water. If a thermostat is used to ensure water temperature in the pipes never exceeds 50-60°C, no additional treatment is needed.

Water quality and detergents

Knowing the hardness of your water is also important in the choice of laundry detergents, in order to avoid excess detergents and phosphates (fertilisation) in the residual water and, therefore, excessive eutrophication of the receiving waters. As calcium in the water has a negative effect on the cleansing power of detergents, calcium stabilisers are added, usually in the form of phosphates. The exact amount of these products used should be determined based on the hardness of the water, and we recommend following the instructions that can be found on the packaging of all products for sale in the Grand Duchy of Luxembourg.

Water treatment equipment

For health reasons, it is important to regularly maintain equipment. Poor maintenance may cause water to become contaminated due to a proliferation of bacteria, especially in ion-exchange resins.

The table below provides an overview of treatments that can be carried out depending on the category of water hardness:

Hardness category Hardness in German degrees Hardness in French degrees Water Treatment


< 8.4

< 15


no treatment





no treatment


> 14

> 24.9


treatment of hot water with polyphosphates

*1 German degree = 1.79 French degrees = 0.18 mol/m³

Water softeners replace calcium and magnesium molecules (which are the main contributors to water hardness) with sodium molecules so as to prevent calcium precipitation.

You are strongly advised not to plug the softener into the cold water system, as a high concentration of sodium in your cold water is not healthy.

Above all, you should carefully follow the installation and maintenance instructions for this equipment to prevent bacterial contaminants from developing in your tap water. Although a high calcium content can cause calcium deposits in industrial installations and home appliances, it is beneficial for human health.

the department

Contact details

338, rue du Rollingergrund
L-2442 Luxembourg

Opening hours


8:00–12:00 and 13:00–17:00

Out-of-hours service