The present invention describes a method for regulation of a hybrid device allowing purification and either recycling or separation of water, said method comprising measuring a water quality parameter in water in the hybrid device in a measuring point; deciding the limit value of the water quality parameter based on measurement of the water quality parameter, said limit value being a reference for a limit value for clean water; and if the water quality parameter in the measuring point is outside of the limit value of the water quality parameter then separating the water, and otherwise recycling the water in the hybrid device.
