Due to its high toxicity, the limit value of the heavy metal lead for drinking water has been lowered more and more in the past decades. Especially infants, small children and pregnant women are to be particularly protected in this way. The historic value of 40 µg/L, which was still valid in the 1970s, was therefore reduced in the future to one eighth - namely to 5 µg/L –with the new Drinking Water Directive issued in December 2020. The article explains how the implementation can work for materials that come into contact with drinking water.
It has been known for years that the heavy metal lead is harmful to health. However, lead pipes were installed in certain regions until the 1970s, which often meant that the first migration limit value of 40 µg/L set for drinking water could not be complied with. Lead is particularly unsuitable for infants, small children or pregnant women, so that the drinking water was no longer suitable for food preparation. The already lowered limit of 25 µg/L from 2003 was therefore lowered a second time in 2013 to 10 µg/L.
In 2017 - 2019, more than 20 water supply areas in Germany were still unable to consistently comply with the limit value for lead at the tap. This is an indication of lead pipes still present in or metallic materials that do not comply with the generally accepted rules of technology. In order to further dam health hazards, with the publication of the new EU Drinking Water Directive 2020/2184 on December 16, 2020, in addition to stricter limits for Legionella, chlorate or bisphenol A, above all the limit for lead in materials in contact with drinking water was lowered again. With entry into force on 12.01.2021, the implementation into national law is thus initiated by 12.01.2023. In a period of 15 years after the entry into force of the present directive, the parameter value for lead should be 5 μg/L by the end of the transition period. New materials in contact with drinking water, whether intended for utility or domestic installation purposes, should comply with the new guideline value in accordance with the new directive for approval.
In order to prove that no impairment of drinking water quality is caused, the Federal Environment Agency has published a staggered stagnation test of drinking water with the recommendation "Assessment of drinking water quality with regard to the parameters lead, copper and nickel". Here, the drinking water with the quality supplied by the water supply company should be taken directly from the tapping point, after stagnation times between 2 and 4 hours, and the value for lead should be determined. Such a test is offered by the test centre.
For the inclusion of new metallic materials in the positive list of the evaluation criteria document for metallic materials, TZW offers testing in accordance with DIN EN 15664-1 and DIN EN 15664-2. Here, the release of metals from the metallic material into the drinking water is to be determined by taking samples over a period of 26 weeks. These are measured after different stagnation times. For lead, the determined value shall already correspond to only 50% of the limit value of the drinking water ordinance, i.e. 5 µg/L. Under testing with the help of three test waters, an assessment should be possible for the drinking waters distributed in Europe. Here, in addition to very hard, neutral water, soft, slightly acidic as well as soft, alkaline water is used. The positive list of the metal assessment basis will have a different face in the future, but this also offers the opportunity for new materials.
Literature links (in German):
- RICHTLINIE (EU) 2020/2184 DES EUROPÄISCHEN PARLAMENTS UND DES RATES vom 16. Dezember 2020 über die Qualität von Wasser für den menschlichen Gebrauch (bundesgesundheitsministerium.de)
- Presseinformation Nr. 6/2008 "Blei im Trinkwasser" (umweltbundesamt.de)
- Bericht "Qualität von Wasser für den menschlichen Gebrauch (Trinkwasser) in Deutschland" (umweltbundesamt.de)
- Ratgeber "Rund um das Trinkwasser" (umweltbundesamt.de)
- Ratgeber "Trinkwasser aus dem Hahn" (umweltbundesamt.de)
- Probennahmeempfehlung (umweltbundesamt.de)