Abstract: System for supply of liquid comprising a discharge point (15), a liquid line (5, 5, 12, 16, 18) connecting the discharge point to a flow regulator (2, 41), which in an active mode supplies liquid from a source (1, 40), through the liquid line to the discharge point and which in an inactive mode prevents liquid flow through the line; and a liquid purifier (6), which is connected to the fluid line, between the discharge point and the flow regulator and which comprises a UV-light source (10). For achieving reliable automatic activation of the UV light source upon activation of the flow regulator, the flow regulator is electrically controlled and means are provided for detecting a supply current to the flow regulator and in response thereto activate the UV-light source.