"Mobile" chemicals - when filters become useless

German Environment Agency wants better protection of drinking water against "mobile" contaminants

clear water is poured in a glassClick to enlarge
Drinking water in Germany is "very good"
Source: bigfoot / Fotolia.com

"Mobile" chemicals are what the UBA is calling chemicals which have entered the water cycle because they do not bind to solids such as sand or activated carbon. They are therefore penetrating natural barriers like the riparian zones of rivers and lakes and cannot be removed by the artificial filters at water works. "In worst case these mobile industrial chemicals end up in our drinking water. This is only happening in a few cases so far and very seldom in concentrations which may be harmful to health. To protect our health it is important to take a closer look at mobile chemicals", said UBA's President Maria Krautzberger. "The new criterion concerning the mobility of chemicals will help manufacturers to first identify 'mobile' substances, and secondly, industrial operators can either reduce emissions to the environment or switch to less harmful chemicals." A list of mobile substances which has yet to be drawn up could help water utilities in their monitoring activities.

The new proposal calls for a paradigm shift in chemicals evaluation. Up to now companies have evaluated industrial chemicals according to the EU REACH regulation, primarily with a view to whether they are persistent, bioaccumulative and toxic (PBT criteria). Substances which are persistent (P) are resistant to degradation in the environment; bioaccumulative (B) means they can concentrate in the organisms of man, animals or plants, and toxic (T) refers to their toxicity. The authorities consider them to be substances of very high concern which may be banned in Europe. However, the PBT criterion is limited in its scope: it only covers chemicals which are bioaccumulative and which might be absorbed from food. It does not include chemicals which are suspended in the water cycle and might therefore enter the drinking water cycle. 

UBA is recommending that industrial chemicals be assessed not only on the basis of their PBT properties, but also on their mobility, that is their PMT properties. This means early identification of substances which are persistent (P), mobile (M) and toxic (T). Mobility and persistence make it possible for chemicals to be transported across great distances in rivers, lakes, creeks and groundwater and for long periods of time. If these substances are also toxic, UBA believes there is a need for action on the part of industry, regulatory authorities and water utilities. 

The sources of Germany's drinking water are often located in protected areas in which industrial chemicals are either banned or may only be applied under strict conditions. However, their protection is not equally effective everywhere. In places where drinking water is extracted from surface water or through bank filtration in particular, persistent and mobile substances pose a critical challenge to water purification. To degrade them, for example by UV radiation or ozonation, or filtering (by activated carbon or membrane filtration) requires a great deal of technical and financial input, not to mention energy. "The best approach is to follow the precautionary principle and avoid contamination of the water cycle at the development phase and in the use of industrial chemicals," says Maria Krautzberger. 

Drinking water in Germany is extracted from ground and spring water (70%) and from reservoirs, rivers and bank filtration. Drinking water quality in Germany is very good across the country. To ensure that the water cycle remains as free as possible of chemicals in future, UBA is hosting an event on 4 May 2017 for an exchange between representatives of the chemical industry and the water utility in Berlin. 

Further information: 
Neumann, M. (2017) Vorschlag für Kriterien und ein Bewertungskonzept zur Identifizierung von persistenten, mobile und toxischen (PMT-) Stoffen zum Schutz des Rohwassers zur Trinkwassergewinnung unter der EU-Verordnung REACH , Zbl. Geol. Paläont. Teil I, Jg. 2017, Heft 1, 91-101. 

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