Traces of radiation – GRS develops database on radionuclides in drinking water

Water means life. Every living creature needs water, humans need it for drinking, cooking, personal hygiene, washing up and doing the laundry. If water is not distilled, it is a solution in which substances and microorganisms naturally occur. The situation is no different with German tap water. In order for this to be classified as drinking water, the German Drinking Water Ordinance (Trinkwasserverordnung – TrinkwV) requires that any harm to human health through its consumption or use must be excluded (§ 4(1) TrinkwV), To ensure the quality of drinking water, the legislator has defined various criteria. In addition to more general indicators (colouring, taste, odour etc.), these are primarily microbiological and chemical limits. Furthermore, Annex 3a TrinkwV contains limits for radioactive substances.

Drinking water can naturally contain uranium

In fact, drinking water can contain, for example, uranium: The radioactive element occurs relatively frequently in the earth's crust in the form of mineral compounds. When water flows through rocks containing uranium, it naturally absorbs the water-soluble heavy metal.

Consumed in small quantities, however, radioactive substances in general and uranium in particular need not have any harmful effect on human health – freely adapted from Paracelsus: the dose makes the poison. The limits to be complied with are intended to ensure that this dose remains within a range that is harmless to humans. To be on the safe side, the applicable limits were chosen very carefully. The limit for uranium according to the Drinking Water Ordinance, for example, is 10 μg/l (i.e. 0.00001 g/l), although according to the German Environment Agency, the radiotoxicity of uranium only has a health significance from 60 – 90 μg/l. The reference value in the USA has been set at 30 μg/l by the independent United States Environmental Protection Agency (EPA).

Mandatory measurements for radionuclides of natural origin

In 2015, the Third Ordinance (which implements Council Directive 2013/51/EURATOM in national law) amending the Drinking Water Ordinance introduced, among other things, obligations regarding the analysis for radioactive substances (§ 14a TrinkwV). It obliges owners of water supply facilities to conduct initial analyses of drinking water for radionuclides of natural origin, to complete these analyses by November 2019 and to report the results to the competent authorities of the Länder. In order to compensate for any seasonal or operational fluctuations, a total of four measurements had to be carried out within a period of twelve months.

Such measurements are not only interesting with regard to the question whether the analysed drinking water meets the German and European drinking water requirements. They are also relevant for radiation protection in order to better assess the natural radiation exposure of the population via the drinking water path. For this reason, the Federal Office for Radiation Protection, for example, carried out a research programme from 2003 to 2008 on the content of natural radionuclides in drinking water. At that time, the studies were limited to focal points due to the enormous amount of work involved: Thus, only selected sites were examined and samples were only taken once.

Data from around 15,000 water supply facilities

Due to Council Directive 2013/51/EURATOM laying down requirements for the protection of the health of the general public with regard to radioactive substances in water intended for human consumption, all of the approximately 15,000 water supply facilities had to measure their water for radionuclides. BfS has now commissioned GRS to determine all water supply facilities in Germany and to query the values measured there. In addition, the research team is to set up a central database and compile information on the water supply facilities relevant with regard to radiation protection. This concerns for example

• general information about the water supply facility,
• results relating to Annex Зa TrinkwV, broken down into the individual quarterly measurements for radon and the measured quantities used to evaluate the reference dose,
• the origin and treatment of the water, including geological information on the underground, and
• further parameters to be considered according to the Drinking Water Ordinance which could be relevant for the examination and characterisation.
• Data enable more detailed assessment of radiation exposure

The scientists are to examine the data in the context of Annex 3a submitted by the water supply facilities to determine whether they meet the requirements of the Drinking Water Ordinance and the Guidelines for the analysis and assessment of radioactive substances in drinking water by implementing the Drinking Water Ordinance (Leitfaden zur Untersuchung und Bewertung von radioaktiven Stoffen im Trinkwasser bei der Umsetzung der Trinkwasserverordnung). It was published in 2017 by the Federal Ministry for the Environment (BMU) and contains recommendations from the Federal Ministry of Health (BMG), the Federal Office for Radiation Protection (BfS), the German Environment Agency (UBA), the competent Land authorities, the German association of the gas and water industry (DVGW) and the German Association of the Energy and Water Industries (BDEW).

The BfS intends to use the processed data to obtain a comprehensive spatial and temporal overview of the radionuclide contents of natural origin in drinking water in Germany. This will enable the experts to assess the radiation exposure of the population in more detail and, if necessary, to derive protection concepts. Furthermore, more specific recommendations could be made for operators of water supply facilities and for the competent health authorities, the population could be informed more specifically, and participation in committee work (e.g. WHO, IAEA) could take place more effectively.