Abstract: There is provided a water purification catalyst element (100). The catalyst element (100) comprises a porous support (102) having a first surface (106) and a second surface (110). The first or the second surface (106, 110) delimit a conduit (114) through the catalyst element (100). A material (104) comprising a noble metal is supported on the porous support (102). At least the first surface (106) is coated with a coating material (108) permeable to hydrogen gas and impermeable to water, and at least the second surface (110) is water-permeable. This catalyst element (100) can selectively convert nitrites and/or nitrates to N2 gas and can be used to provide a cost efficient and/or maintenance free water purification setup. There is also provided a water purifier (200) comprising the catalyst element (100), a beverage maker (300) comprising the water purifier (200), a method (1800) of water purification and a method (1900) of making the catalyst element (100).