Guidelines create basis for ensuring the quality of drinking water

Water reservoir Source: © Joachim Donath

The guidelines on the analysis and assessment of radioactive substances in drinking water create the basis for the long-term safety of drinking water. They standardise both the analysis and its implementation by the competent federal state authority. They came into effect under the careful guidance of the Federal Office for Radiation Protection (BfS) and replaced an earlier version from 2012.

According to the Drinking Water Ordinance, water suppliers are generally obliged to analyse the concentration of radionuclides in drinking water. The guidelines contribute to a consistent understanding of the legal requirements.

The Federal Ministry for the Environment, Conservation, Nuclear Safety and Consumer Protection (BMUV), the Federal Office for Radiation Protection (BfS), the Federal Ministry for Health (BMG), the Federal Environment Agency (UBA), the competent state authority, the German Technical and Scientific Association for Gas and Water (DVGW) and the Federal Association of the Energy and Water Industry (BDEW) recommend the application of the drinking water guidelines. The guidelines reflect the current state of scientific knowledge. The aim is to continually ensure the long-term high quality of drinking water in Germany.

Development of the guidelines: First BfS study in 2009, European regulations and ordinances

On behalf of the Federal Ministry for the Environment, the BfS carried out an extensive research programme from 2003 to 2008 to determine the content of natural radionuclides in drinking water and the resulting radiation exposure. The BfS published the study "Radiation exposure through natural radionuclides in drinking water in the Federal Republic of Germany" in 2009 (in German only).

The study covered large parts of Germany, with experts analysing 582 drinking water samples. In urban areas, these came mainly from large water supply facilities, some of which supply several million people with drinking water. In addition, targeted samples from water supply facilities in areas with elevated natural radioactivity were analysed from the states of Bavaria, Saxony, Baden-Wuerttemberg, Thuringia, Rhineland-Palatinate and Saxony-Anhalt. Because of this approach, the data acquired is representative for the purpose of the task.

Result: radiation exposure for people through radionuclides in drinking water is low

The study showed that exposure through natural radionuclides in drinking water in Germany can be classified overall as low. According to the study, adults are exposed to an average radiation of around 0.009 millisieverts per year due to radionuclides in drinking water. For infants this value is on average around 0.05 millisieverts. By comparison, the natural radiation level to which the population as a whole is exposed to on average per year is around 2.1 millisieverts. However, depending on the properties of the bedrock, drinking water can show an increased content of natural radionuclides.

Between 2009 and 2012, an interdisciplinary working group led by the BfS and consisting of representatives from ministries, radioactivity measuring institutions of the federal states, analytical laboratories and drinking water associations developed a guide for the analysis and assessment of radioactivity in drinking water specifying the existing requirements on a recommendatory basis.

With Directive 2013/51/EURATOM published in 2013, the Council of the European Union laid down requirements for the protection of the health of the general public with regard to radioactive substances in drinking water and obliged EU members states to implement the guideline in their national legislation by 28 November 2015. In Germany, the implementation took place with the third ordinance amending the Drinking Water Ordinance (TrinkwV) of November 18th 2015.

Requirements for practical implementation

The guidelines specify which requirements the respective testing laboratories must meet when taking samples – for example which testing methods are to be used or how often samples are to be taken. For certain radionuclides, the ordinance also indicates reference activity concentrations that can be used to compare with the measurement results.

These instruments form the basis for imposing measures in individual cases to reduce radionuclide concentrations in drinking water and therefore for ensuring the quality of drinking water and protecting human health.

The testing and evaluation of parameters related to radioactivity in drinking water as laid down in the guidelines on compliance with the requirements of the Drinking Water Ordinance may only be carried out by authorized testing laboratories. The competent federal state authority only grants approval to testing laboratory when being accredited according to the current regulations of the Drinking Water Ordinance. It is also possible that laboratories can be accredited for the testing of a single parameter.

The accredited laboratories have to participate in external quality assurance programs. With regard to the determination of natural radionuclides in drinking water, the Federal Office for Radiation Protection (BfS) for example offers interlaboratory comparisons on a regular basis. This is intended to ensure the ongoing high quality of drinking water in Germany.