A water purification apparatus for producing purified water, the water purification apparatus comprising - a Reverse Osmosis, RO, device, arranged to produce a purified fluid flow and a reject fluid flow, the RO-device comprising a RO-membrane, a feed inlet, a permeate outlet and a reject outlet; - a feed fluid path arranged with a RO-pump to pump feed fluid to the feed inlet; - a heater arranged to heat the purified fluid produced by the RO-device downstream the RO-device; - a first fluid path arranged to circulate heated purified fluid from a point downstream the heater to a tank arranged in the feed fluid path inside the water purification apparatus, wherein the first fluid path includes the RO-membrane such that the heated purified water is passed through the RO-membrane; - a second fluid path arranged to transport the heated purified fluid inside the water purification apparatus; - a valve arrangement arranged to direct the heated purified fluid into the first fluid path or the second fluid path; - a control unit configured to control cleaning of the water purification apparatus, the control unit being configured to cause the water purification apparatus to: o control heating, with the heater, of the purified fluid from the RO-device; o control the valve arrangement to recirculate the heated purified fluid in the first fluid path, until a first temperature dependent criterion is fulfilled; o control the valve arrangement to re-direct the heated purified fluid to flow in a second fluid path of the water purification apparatus, in response to the first temperature dependent criterion is fulfilled; and o control heating, with the heater, of the re-directed heated purified fluid in order to fulfil a second temperature dependent disinfection criterion for the second fluid path wherein only the RO-pump is used to produce a fluid flow in the first fluid path and the second fluid path in order to fulfil the first temperature dependent criterion and the second temperature dependent disinfection criterion. - a Reverse Osmosis, RO, device, arranged to produce a purified fluid flow and a reject fluid flow, the RO-device comprising a RO-membrane, a feed inlet, a permeate outlet and a reject outlet; - a feed fluid path arranged with a RO-pump to pump feed fluid to the feed inlet; - a heater arranged to heat the purified fluid produced by the RO-device downstream the RO-device; - a first fluid path arranged to circulate heated purified fluid from a point downstream the heater to a tank arranged in the feed fluid path inside the water purification apparatus, wherein the first fluid path includes the RO-membrane such that the heated purified water is passed through the RO-membrane; - a second fluid path arranged to transport the heated purified fluid inside the water purification apparatus; - a valve arrangement arranged to direct the heated purified fluid into the first fluid path or the second fluid path; - a control unit configured to control cleaning of the water purification apparatus, the control unit being configured to cause the water purification apparatus to: o control heating, with the heater, of the purified fluid from the RO-device; o control the valve arrangement to recirculate the heated purified fluid in the first fluid path, until a first temperature dependent criterion is fulfilled; o control the valve arrangement to re-direct the heated purified fluid to flow in a second fluid path of the water purification apparatus, in response to the first temperature dependent criterion is fulfilled; and o control heating, with the heater, of the re-directed heated purified fluid in order to fulfil a second temperature dependent disinfection criterion for the second fluid path o control heating, with the heater, of the purified fluid from the RO-device; o control the valve arrangement to recirculate the heated purified fluid in the first fluid path, until a first temperature dependent criterion is fulfilled; o control the valve arrangement to re-direct the heated purified fluid to flow in a second fluid path of the water purification apparatus, in response to the first temperature dependent criterion is fulfilled; and o control heating, with the heater, of the re-directed heated purified fluid in order to fulfil a second temperature dependent disinfection criterion for the second fluid path