The rules for abuse of a dominant position regarding the prices of water suppliers have been in the focus since the decision of the BGH regarding the water supplier Wetzlar. This decision led to numerous procedures against water suppliers and was considered in the latest amendment of the German antitrust law. The work analyzes the scope of the antitrust law and the legal and actual problems of the practice on the basis of the interpretation by the BGH. The author comes to the conclusion, that the current practice of the rules for abuse of a dominant position regarding the prices of water suppliers is not only problematic, it is unconstitutional.