Abstract: An apparatus for extracting water from the atmosphere has a chamber or a pair of chambers connected to a compressor by a valve controlled in its operation in response to an operating condition in the chamber or chambers. A suction fan is connected to the chamber or chambers to move air through the chambers. A further valve is arranged in the respective inlet to the chamber or chambers to facilitate an expansion condition or effect in the respective chamber. Where two chambers are used they operate in alternate fashion so that heat is supplied to one chamber while heat is being withdrawn from the other chamber and vice versa, and both chambers are controlled in response to the respective operating condition therein.