The objectives of this study were to: meet Information Collection Rule (ICR) requirements by conducting pilot-scale testing of the nanofiltration process; determine if nanofiltration at the Canoe Brook Station would meet anticipated DBP regulations; and, assess the operational issues and cost implications of using a dual membrane system on a surface water supply. The study was conducted under one set of operation conditions for the nanofiltration unit, 90 percent recovery, using a constant water flux through the nanofiltration membrane. The critical operating parameter was the water mass transfer coefficient (MTCw), a measure of the rate of water flow through the semipermeable membrane barrier layer and any material (foulant) that accumulates at the membrane surface or within the membrane barrier layer. In accordance with the ICR Manual, chemical cleanings due to membrane fouling were required when there was a 20 percent decrease in the MTCw. During the test, rapid increases in transmembrane pressure (TMP) due to a change in source water quality required that the microfiltration flux be reduced, so that the cleaning frequency could be reduced. At the end of the testing period, residual chlorine was recorded to determine the chlorine demand for each sample, and the samples were analyzed for trihalomethanes (THMs), haloacetic acids (HAAs), and TOX.