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Water Quality

To secure the excellent quality of Berlin’s drinking water now and in the future, we monitor it continuously and at each point in the drinking water cycle – in the soil, in the wells, in our waterworks, in the pipelines and at the user outlet.

Drinking Water Ordinance

As the legal basis, the German Drinking Water Ordinance (Trinkwasserverordnung - TrinkwV) requires a high quality, from the water supplier through to the tap in the home.

The consumption or use of water must not endanger human health at any time – is what the Drinking Water Ordinance stipulates. The water supply companies that operate the supply networks and the owners or operators of drinking water installations, i.e. home owners and managers, must take this into account. This obligation does not exist for home owners who use their property for themselves only or for tenants.

To secure the legally specified high water quality, the companies or persons responsible must meet the following requirements:

  • The chemical and microbiological quality of water must meet the requirements of the Drinking Water Ordinance at all times. The local health authorities must monitor this.
  • Recognised rules of good engineering practice must be followed in the abstraction, treatment and distribution of water. Among other things, this means the provisions of the German Institute for Standardisation (Deutsches Institut für Normung - DIN) and the German Technical and Scientific Association for Gas and Water (Deutsche Verein des Gas- und Wasserfaches - DVGW).


The legislator sets the highest requirements for drinking water. According to the Drinking Water Ordinance (TrinkwV) it must be clear, colourless, odourless, cool, flawless taste and without any health damaging properties.

We comply with these regulations and in some cases we achieve values that are significantly below the legally defined limits. To achieve this, we test the water quality along all the stations of the drinking water cycle continuously. Starting with the groundwater, we keep a continuous eye on our more than 2,500 monitoring wells. We also take samples directly from our wells and re-examine the groundwater critically under the microscope directly after it has been pumped to the surface. The waterworks carry out daily monitoring to determine the chemical and biological composition of the treated drinking water. This is supplemented by permanent measurement of indicator parameters in real time.

To ensure that the water quality is not impaired on the way to the consumer – perhaps due to construction work or leaks in the pipe network – samples are taken at dense spacings along the way through the network and at 180 Berlin consumers. These samples are then analysed in our accredited laboratories. The dense analysis chain ensures that we can detect and remove contamination in the drinking water cycle at any time and in good time.

This quality is natural in origin: Berlin’s drinking water is a pure natural product, which we completely abstract from our regional groundwater. Ideal geological conditions, extensive water protection areas and our strict precautionary principle ensure the highest water quality.

As drinking water and for use in households, our water needs no aftertreatment whatsoever. Our complex wastewater treatment, the large water protection areas in the city and the soil layers that clean the water naturally, all ensure good groundwater. In our waterworks we merely reduce the iron and manganese it contains, which impair the taste and can colour the water, but are not harmful to health. There are no chemical additives. With our drinking water you therefore enjoy pure nature.

We pay particular attention to the natural management of our resources. This includes natural water treatment, groundwater replenishment and thorough treatment of the wastewater, which flows back into the natural cycle after use.


Berlin’s drinking water contains minerals and trace elements. It is abstracted from the groundwater resources of the Berlin glacial valley and is top quality. Berlin’s water is in its natural state and does not have to be chlorinated. Additives, such as fluorides to prevent tooth decay, are not used.

Please note: Drinking water is not sufficient to cover the vital need for minerals. It is also important to eat a balanced and healthy diet.

As of 2021 Value in mg/l Limit in mg/l* Recommended daily allowance in mg**
Hydrogen carbonate 254    
Calcium 110   800
Magnesium 11   375
Potassium 5   2,000
Iron < 0.05 0.2 14
Sodium 38 200  
Sulphate 105 250  
Chloride 56 250 800

*Limits under the Drinking Water Ordinance (Trinkwasserverordnung - TrinkwV)
**Recommended Daily Allowances (EU-RDA) acc. to Directive 90/496/EEC

Trace substances

Did you know that water in Berlin is managed in a cycle? This functions almost naturally when we treat groundwater without chemical additives and distribute it in the city through our pipes. We take back the used water, pipe it through sewers into the wastewater treatment plant and after treating it we return it to nature. The greatest challenge lies in also filtering out the invisible pollutants. This is because, wittingly and unwittingly, humans leave behind many microscopically small traces which can only be removed by complex processes.

Questions and answers on the subject of trace substances

Water hardness

Berlin’s water contains many valuable minerals and trace elements. With a total hardness of 14 °dH, its character tends to be hard. What is casually called "chalky" is good for the human body, but not for the coffee maker, dishwasher and other household appliances.

What does water hardness mean?

Berlin’s water contains many valuable minerals and trace elements. Under the action of water molecules, the minerals are decomposed into ions with hydrate shells and are responsible for the electrical conductivity, the pH value and the calcite dissolution capacity of water.

It is commonly known that hard water requires more soap for washing than soft water. The so-called water hardness is traditionally given in “German hardness grades" (°dH). Until now it was disputed whether this fully covered the magnesium content of water. Today we know that it is not covered by it.

It is therefore correct to talk of "calcium deposits” (limescale) from Berlin’s water, because they do not contain any magnesium carbonate, but instead solely calcium carbonate. For this reason, the wording of § 9 of the German Detergent and Cleaning Agent Act (Wasch- und Reinigungsmittelgesetz) is applied strictly when determining the hardness range in Berlin:

  • “Medium hardness range: 1.5 to 2,5 millimole calcium carbonate per litre”
  • “Hard hardness range: more than 2.5 millimole calcium carbonate per litre”

The unit millimole per litre (mmol/l) needs some getting used to, but is universal and cannot only be applied to calcium and magnesium, but also to sodium, hydrogen carbonate, chloride, sulphate and other ions in water.

1 mmol/l equals 5.6 °dH.

Traditional expression of the hardness range

Total hardness [°dH] Water character
less than 8.4 °dH soft water
8.4 to 14 °dH medium-hard water
more than 14 °dH hard water

*According to the new version of the German Detergent and Cleaning Agent Act (WRMG); enacted
on 1 February 2007 by the German Bundestag,came into effect on 5 May 2007