The prevention of fouling of polysulphone ultrafiltration membranes, used for the purification of natural brown water, was investigated by pretreating the membranes prior to filtration. Polysulfone membranes were pretreated by commercial nonionic surfactants Triton X-100 and Pluronic F108, Specific characterisation techniques, developed by Maartens et al, (1998) and Jucker and Clarke, (1994), were used to determine and compare the effects induced by the adsorption of natural organic matter on the permeability of untreated as well as surfactant treated capillary ultrafiltration membranes. The extent of foulant adsorption and the quality of the resultant permeate solutions were determined by ultraviolet visible-light spectroscopy. The findings of this investigation provides information of importance for the operation of future natural brown water ultrafiltration plants.