Two complementary methods for characterizing membrane surface characteristics under differing solution pH, ionic strength and hardness are presented. These methods are intended to allow quantification of membrane surface hydrophobicity and apparent charge under various conditions. Quantification of these properties would allow direct comparison of different membrane polymers and their properties in contact with a given water. This in turn would allow a more scientific approach to membrane selection for a given source water. Sufficient empirical data have been collected to support the use of nanofiltration membrane separation as a safe effective treatment process for the removal of organic macromolecules from water and prevention of disinfection byproduct formation. However, the raw water conditions which lead to fouling of the membranes by natural organic matter (NOM) have not been systematically studied. This paper presents a portion of a larger study to characterize the membrane surface characteristics and NOM characteristics under certain water conditions. These characteristics could then be correlated to aqueous flux and membrane rejection of NOM.