The objectives of this paper are: to present the efficacy of integrated membrane systems for water treatment in terms of microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF) fouling; and, to relate fouling to capital and operation and maintenance costs for a 100 mgd facility. Three pilot plants were employed for experiments conducted on a reservoir in Northern Virginia in the United States. Two were low pressure membrane plants: a UF pilot which employed a 100,000 molecular weight cutoff membrane fabricated from a cellulosic derivative; and a MF pilot employing a polypropylene membrane with a 0.2 um nominal pore size. Each were designed for permeate flow rates of 5 to 15 gallons per minute. The permeate from these plants fed four separate pressure vessels on the NF plant. Thus, two identical sets of NF membranes received pretreated water from both UF and MF pilot skids. Includes reference, figures.