Abundant supplies of safe drinking water are among
Switzerland’s most valuable natural resources, with groundwater accounting for
80% of the total. A third of this groundwater, in turn, is fed by infiltrating
river water. Although contaminants and pathogens are filtered out as they pass
through the soil, this natural protection system is not infallible. That makes
it all the more important for river water to be kept as clean as possible, and
for interactions between river and groundwater to be carefully observed.