Abstract: A water purifier for home use, irrigation systems used for crop cultivation or the pharmaceutical industry includes a water inlet for a water to be purified and a water outlet for a purified water. A water treatment chamber is fluidly connected to the water inlet and the water outlet. The water treatment chamber is confined by a chamber wall. The water purifier includes a high-voltage plasma unit for generating a cold plasma within the water treatment chamber. The plasma unit has a first electrode and a second electrode. The first electrode is arranged inside the water treatment chamber such that, during use of the water purifier, it is contacted by the water. The second electrode is disposed spaced apart from the first electrode and electrically insulated therefrom by a dielectric. The water purifier further relates to a water purification system.