The microfiltration of fractionated NOM identified that the main contributor to hydrophobic microfiltration membrance fouling was the low molecular weight neutral hydrophilic fraction. Attempts to identify a suitable process for selectively removing this fraction of NOM from water before microfiltration were unsuccessful, and led to the idea that the membrane surface should be modified to enhance rejection of this fraction of NOM. Polyelectrolytes were grafted onto the surface of polypropylene membranes using expertise developed at the Institute for Polymer Research (IPF) in Germany. Experiments with membranes grafted with anionic polyacrylic acid hydrophilic polymers demonstrated that fouling rates were 50% lower than for the non-grafted membranes and rejection of NOM was not compromised.