The Deep Aquifer Treatment System (DATS) is an 8-million gallon per day (mgd) nanofiltration (NF) color removal treatment plant that has operated for the past six years. When the plant was initially put in operation monthly membrane profiles for conductivity (EC) and UV₂₅₄ absorbance were routinely conducted on permeate samples from each of the three treatment trains pressure vessels to monitor for potential membrane system integrity including permeate water quality degradation due to compromised interconnectors, brine seals, end adaptors, o-rings and the membranes. A reduced membrane integrity sampling regime was adopted in 2004 based upon the excellent performance of the membrane system. Towards the end of 2006 and through the spring of 2008 membrane performance had degraded and it appeared that membrane replacement in several pressure vessels may have been warranted. Staff then renewed its membrane profiling to identify the apparent membrane performance "breeches" that resulted in significant savings over the membrane replacement option. This paper reviews and demonstrates the importance of implementing standardized membrane profiles and profiling as troubleshooting tools, and presents results of the findings at the DATS facility that assisted operators in correcting "breeches" in membrane system integrity that are consistent with what are considered the standards for the industry. Includes 3 references, tables, figures.