Inorganic chemical quality of European tap water: Geographical distribution and regulatory compliance

579 tap water samples were collected at the European scale and analysed in a single laboratory for more than 70 parameters. This dataset is analysed in terms of the spatial distribution of the analysed parameters to detect... [ view full abstract ]

579 tap water samples were collected at the European scale and analysed in a single laboratory for more than 70 parameters. This dataset is analysed in terms of the spatial distribution of the analysed parameters to detect some key processes that control tap water geochemistry at a continental scale. These parameters are also compared to European drinking water regulations.

The use of surface waters and poorly-buffered silicic aquifers for drinking water supply in Norway, Sweden and Finland is reflected in low concentrations of Ca, Mg, Sr and Li. At the same time, these tap waters show the highest concentrations of the rare earth elements, probably reflecting their geological availability and the generally low pH of raw water sources.

Geology is an important factor determining the regional distribution patterns for some elements; e.g., high values of Cr and V appear to be influenced by the distribution of mafic and ultramafic rocks in Europe.

Water treatment is, for example, reflected in especially high P values observed in the United Kingdom, where phosphate is used to fight plumbosolvency from the water distribution network.

For most parameters a level of 99% or better compliance with international drinking water norms is achieved. A dataset based on a greater number of tap water samples (N = 1000 – 2000), evenly distributed over Europe would deliver highly relevant information for scientists, water managers and politicians, highlighting the different raw water sources, the differences in geology but also water treatment practices at the European scale.