The invention relates to a method, a treatment installation (26) and a treatment component (29) for the destruction of microorganisms and macroorganisms in a flowing liquid. The destruction takes place instantaneously, while the liquid passes through said component (29) in said installation (26). The treatment is performed in that the liquid is led in a forced movement through a passage (49) in a case (48) of electrically insulating material. In flowing through the passage, the liquid is subjected to an influence from one or more alternating current fields in that alternating current is short-circuited in the flow of water through alternating current conductors (50) that are arranged internally in said case (48).