Pollutants in drinking water - what are there and what effects can they have?

The German drinking water is controlled very strictly. The limits for all potentially hazardous substances are also very low. Some pollutants can still occur in drinking water. Which substances may possibly be hazardous to health and what effect they have is therefore explained here.

Drinking water parameters and limit values

For drinking water testing, 33 parameters are currently being checked.

On the other hand, the recommendation of the World Health Organization WHO provides just under 200 parameters that should be examined. However, in European countries, not all of these parameters are checked individually for drinking water supply and the necessary tests, but are often based on the indicator principle.

The presence of a single substance can often be used as a reliable indicator of the presence of a whole group of substances that affects the water. From the occurrence of individual substances can often be computationally closed to the amount of a whole range of other substances in the water, so that a complex single test can be omitted.

In the case of pesticides, the zero principle is also checked - if more than five substances exceed the detection limit, the water is automatically considered as contaminated. This method was chosen because pesticides have different degradation products that can interact with each other in addition. An individual proof of all these substances would therefore be complex and only slightly effective.


In water management both values ​​- the MKZW and the MKW - play an essential role.

The MKZW, the maximum concentration target value, indicates the limit value to which no information is yet available and in which a health hazard can be relatively reliably excluded, even with continuous use in conventional amounts.

The MKW, the maximum concentration value, on the other hand, is the value aimed at by the waterworks during the treatment.

Both values ​​are, according to the current state of knowledge, rather good guidelines for healthy adults - however, it is not taken into account that infants, children, the sick and old people with poor health can often have a significantly lower tolerance for individual substances. This is also the main criticism of the limits.

Pollutants in small quantities

Due to the applicable limit values, individual pollutants can remain in drinking water even after treatment. In the permitted concentrations, however, they are relatively safe not harmful to health. Specifically, these are:

  • small amounts of germs and bacteria
  • Prions (diseased proteins, for which there are no technical removal possibilities yet)
  • minor traces of medication
  • Traces and degradation products of pesticides
  • small traces of heavy metals
  • small traces of female hormones
  • Nitrate and nitrite (traces)
  • generally chemical substances below the applicable limits
  • Algae or algae remains or algae spores in very small quantities (extremely rare)

Fabrics that may result from the house installation

  • rust
  • Lead in high quantities with old lead pipes
  • dangerous germs due to contamination of water filters
  • Legionella
  • Copper and zinc
  • antimony
  • Nitrate and nitrite can also come from defective domestic water installations (soiling)

Tips & Tricks

In order to determine the degree of contamination of drinking water safely, it is advisable to have a drinking water test of domestic tap water carried out. A comprehensive check ensures that the drinking water from the line is actually not contaminated.

Video Board: When is water safe to drink? - Mia Nacamulli