A supply of water that is used to remove heat from a process that operates at a temperature of less than 100ºC. The water, which may be chilled or at ambient temperature, is used as a heat transfer medium or coolant, and contacted with a hot process stream either by direct contact or directly such as through the walls of a heat exchanger. After being heated, the water may be reused by removing the heat gained through a cooling tower, with a make-up to allow for loss from evaporation. Depending on the quantities required and the type of application, the water may be freshwater taken from a river, such (p. 83) as used in a nuclear power station, or saltwater from the sea although there are associated corrosion issues. The deposition of dissolved salts can also lead to fouling issues.