The fouling characteristics of ultrafiltration membranes used in drinking water were investigated when used alone and when used in an integrated biofilter-membrane system to treat a humic-acid laden solution. Membrane strands from sacrificial modules operating in parallel with bench-scale modules were analysed from both systems (with and without pretreatment). Chemical and microbiological analyses were performed on these strands together with different process streams along the treatment train. Microscopic observations performed on the sacrificial membrane strands revealed that most of the fouling material was organic in nature with high numbers of viable microorganisms. When comparing their fouling characteristics, a positive effect from the biofilter was observed on the performance of the membrane with pretreatment, decreasing in general the amount of material deposited and reducing the fouling rate. Membranes were tested at two different permeate fluxes; this variable did not have an effect on the overall amount of material deposited, but it significantly impacted the membrane fouling rate.