Abstract: Liquid purifying apparatus in which an infeed chamber, an evaporator chamber and a condenser chamber are arranged in that order along a flow path. A first inflatable bag is interposed across the flow path between the infeed chamber and the evaporator chamber, and a second inflatable bag is interposed across the flow path between the evaporator chamber and the condenser chamber. These bags are respectively located substantially entirely in the evaporator and condenser chambers, and the bags each comprise a flexible layer of highly absorbent fibrous material including a plurality of plies. The liquid to be purified is introduced into the infeed chamber, and it flows into the evaporator chamber to a level such that a portion of the first bag is immersed in the liquid. The liquid spreads by immersion and capillary action over substantially all of the fibers in the first bag to form thin liquid films along the individual fibers.