A unit for the preparation of cold, purified and carbonated water. The unit comprises a connection for a water supply; an optional sterilisation unit, e.g. in the form of a unit comprising at least one water inlet and at least one hot water outlet for discharging purified water. Further, there is a cooling unit comprising at least one hot water inlet and at least one cold water outlet; a carbonation unit comprising at least one inlet for introducing carbon dioxide into the cold, purified water so as to prepare cold, purified and carbonated water; and a water outlet for the delivery of the cold, purified and carbonated water from the pre-module to a freezing unit of an ice-making unit.