The present invention relates to an apparatus for the treatment of liquids, comprising a filter module with a filter, an inlet for liquid, a first outlet for liquid and a second outlet for filtered liquid, wherein the inlet and the first outlet are positioned on a first side of the filter, and the second outlet is positioned on the second side of the filter, a first UV-treatment module with a first UV-light source, wherein the first UV-treatment module is connected with the first outlet of the filter module and adapted to receive liquid from the filter module, and to expose said liquid to UV-light from the first UV-light source, and a second UV-treatment module with a second UV-light source, wherein the second UV-treatment module is connected with the second outlet of the filter module adapted to receive filtered liquid from the filter module, and to expose said liquid to UV-light from the second UV-light source.