Polymethyl methacrylate-N-vinyl-2-pyrrolidone P(MMA-NVP) copolymer was synthesized in an inert atmosphere by bulk polymerization using azobis-isobuty-ronitrile (AIBN) as initiator. The copolymer was crushed, and ground to a defined particle size and iodinated. The iodinated copolymer matrix was washed thoroughly in a suitable solvent so as to remove any residual iodine and characterized using solubility, swelling, viscosity, FT-IR, and H-1-NMR studies. The :iodinated copolymer was then packed in a refill cartridge specially designed for the purpose. The release of iodide ions from the iodinated matrix was measured in a continuous flow system by directly attaching the cartridge to the water tap and adjusting the flow rate. The water samples were collected at regular intervals and estimated for the concentration of iodide ions using an iodide ion selective electrode. The antimicrobial activity of the copolymer was estimated against bacterial (both Gram-positive and -negative) and fungal species using the zone of inhibition technique. In addition, efficacy of the iodinated copolymer against a variety of microbes was established by inoculating a microbial culture in the water reservoir and measuring the rate of survival of microbes after passing through the copolymer-filled column. The iodinated copolymer was found to be effective against a variety of microbes and remained so completely until 5000 L of water had passed. (C) 2000 John Wiley & Sons, Inc.