The biodegradable organic matter (BOM) that is not removed during water treatment can potentially lead to the proliferation of bacteria along the distribution system, which deteriorates water quality, accelerates corrosion rates of pipes, and can potentially increase the incident of bacteriological diseases. The objective of this project was to collect and anlyze full-scale process data on long-term responses to the utilization of membrane treatment, namely nanofiltration, with respect to its impact on bacterial regrowth potential as quantified by AOC and BDOC. One of the major observations over the sampling period was that nanofiltration had a strong impact on the BDOC concentration of the nanofiltraion treated water. Conversely, nanofiltration did not reject the major fraction of AOC, making the impact of nanofiltration on biostability open to question. This is especially true since better correlations between AOC and microbial parameters have been documented more consistently in the literature than for BDOC.