Metals in drinking water are often attributed to the waterworks. In fact, in most cases, elevated metal concentrations only occur within the domestic installation. The contact between water and pipe materials, fittings, and fixtures determines what ultimately comes out of the tap.
Copper is a typical example. It has been used for decades in drinking water installations and is generally approved. Nevertheless, studies show that copper concentrations can increase significantly, especially after stagnation periods. The cause is corrosion of the inner pipe surfaces, which is influenced by pH value, temperature, and residence time. The German Environment Agency points out that elevated copper levels are often only measured in the household, not in the supply network [UBA, Copper in drinking water, https://www.umweltbundesamt.de/themen/wasser/trinkwasser/trinkwasseraufbereitung/kupfer-im-trinkwasser]
Nickel primarily occurs in connection with chrome-plated fittings and stainless steel alloys. Particularly new components can release measurable quantities in the first few months. Studies show that nickel concentrations are strongly dependent on stagnation time and temperature and can be significantly reduced by briefly flushing. From a regulatory perspective, nickel is therefore a classic "installation parameter" [World Health Organization, Guidelines for Drinking-water Quality, https://www.who.int/publications/i/item/9789241549950]
Lead represents the most critical case. Although lead pipes have been banned in many countries for years, they still exist in old buildings. Additionally, brass alloys with lead content can contribute to its release. Epidemiological studies show that even very low lead concentrations can be relevant for long-term health, especially for children. For this reason, there is no toxicologically safe threshold for lead [European Food Safety Authority, Lead dietary exposure, https://www.efsa.europa.eu/en/topics/topic/lead]
Regulatorily, metals are addressed by limit values that apply at the tap. This acknowledges that the household is a significant source of origin. The European Drinking Water Directive explicitly requires that materials and installations be designed to minimize metal releases [European Commission, Drinking Water Directive (EU) 2020/2184, https://eur-lex.europa.eu/eli/dir/2020/2184/oj]
For everyday life, this means: metal contamination is not an abstract danger, but depends strongly on usage and installation. Stagnation, hot water, and new components increase the likelihood of elevated levels. Brief flushing after a longer period of inactivity can significantly reduce the contamination, but it does not replace material-appropriate planning.
Metals rarely come from the waterworks.
They originate in the last few meters.
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