In Germany, as in almost all industrial countries, active pharmaceutical substances can now be found in virtually all water bodies and occasionally also in drinking water. Even though the concentrations in question tend to be very low, there are initial signs of their  impact on aquatic life. There is no evidence as yet of any acute consequences for human health. It is, however, impossible to rule out long-term consequences from these minimal concentrations or unexpected effects from the interaction between various active ingredients (cocktail effect). At special risk here are sensitive segments of the population such as  children and the chronically ill. There is thus a need for action on precautionary grounds.