Standpipes which are used for drinking water are always provided with a backflow preventer. The backflow preventers are safety fittings which are used to protect water against back syphonage, backflow and back pressure. This prevents the industrial water from getting back into the drinking water line. The backflow preventer BA secures the pipeline network up to and including fluid category 4 according to EN1717. The backflow preventer BA is considered to be state-of-the-art.