The water treatment unit

The invention relates to a water treatment device 1 for installation in a water pipe, comprising a water treatment unit 2 for the treatment of water and a connector 3 for connecting the water treatment device 1 with the water conduit, wherein between the water treatment device 2 and the connection piece 3 a flange 9 with a first flange 12 is provided on the connection piece 3 and a corresponding thereto second flange 13 to the water treatment unit. 2 In order to enable a rapid and safe assembly of the water treatment device 1, the second flange 13 engages behind on the water treatment device 2 of the first flange 12 on the connecting piece 3 keeping.