Drinking Water Ordinance

What does the Drinking Water Ordinance say about water hardness?

The German Drinking Water Ordinance was enacted in 2001, the predecessor law dates back to 1975. It has since been amended several times. The last change took place in 2018. It determines what quality our drinking water must have and how this is to be analyzed and regulated. Rules for water hardness Basically, there are no limit values for the hardness of our drinking water in °dH (degrees of German hardness), because neither very hard nor very soft water is harmful to health. However, according to the Drinking Water Ordinance, the water suppliers are obliged to disclose the degree of hardness in their catchment area. This is intended to protect household appliances, fittings and pipes by allowing consumers to take countermeasures in regions where the water is too hard (targeted water softening). Since 2007, a German regulation in the WRMG (Laundry and Cleaning Agents Act) has defined four degrees of hardness for drinking water:

     soft: up to 7.3 °dH
     medium: 7.31 – 14.0 °dH
     hard: 14.1 – 21.3 °dH
     very hard: over 21.3 °dH

There are regions where 30 °dH is reached and even exceeded.
How is water hardness defined?

It is not clearly defined conceptually. The °dH only indicates the concentration of calcium and magnesium ions. These are the ions of the most important minerals in the water, but its hardness is actually due to a complex system of different chemical balances in the water, which are coupled and influence each other. Among other things, the lime-carbonic acid balance plays an important role in determining the carbonate hardness. However, the Drinking Water Ordinance only stipulates that the °dH be specified. Water hardness is only a relatively subordinate part of this regulation because it has practically no impact on health. It only has significant technical disadvantages if there is too much °dH (hard and even more so very hard water). Devices, fittings and lines suffer greatly from the limescale deposits, resulting in a loss of efficiency and even destruction. Dishwashers, coffee machines, kettles and washing machines work less well and can even suffer serious damage from water that is too hard. In order to avoid this and to provide consumers with an indication of the necessary softening measures, the degree of hardness must be specified.
Notification obligation for the water supply companies

The water suppliers are obliged to report the °dH once a year if nothing changes. If there are changes, they have to react immediately. In order to meet all legal requirements, practically all suppliers permanently publish the °dH in their catchment area online. According to the regulation, you can also choose other ways of publication:

     Publication in the regional press
     Flyer distribution to households
     printed on the water bill

In addition to specifying the °dH, the obligation to publish also includes specifying the sum of alkaline earth metal salts (calcium and magnesium). Of course, given the complexity of processes in the water, this little information seems a bit poor, but the purpose of the drinking water protection ordinance is not to protect technical devices. It clearly defines the aim of protecting human health - which is not suffering from hard water. Our organism even benefits from the minerals in the water. Even more recent adjustments to the regulation never related to the degree of hardness of water, but to nitrates, legionella, pesticides and other pollutants.

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