Evaluation of Long-Term Performance of Point of Use (POU) Systems for Drinking Water Treatment

The U.S. Environmental Protection Agency (EPA) initiated a research program in 2008 at the EPA Test and Evaluation (T&E) Facility in Cincinnati, Ohio to evaluate the performance of various Point-of-Use (POU) treatment devices for providing drinking water in homes and transient non-community water systems, either routinely or as an emergency measure during accidental or intentional contamination events. This paper describes the results of the performance of two POU devices based on reverse osmosis (RO) technology. The POU devices were continuously operated for about 22 months (670 days) to evaluate their long-term performance and challenged with microbiological contaminants at different time intervals to evaluate continued treatment effectiveness. The microbiological contaminant challenge contaminants included E. coli, MS2 bacteriophage, B. subtilis and polystyrene latex (PSL) beads (evaluated as a non-biological surrogate for Cryptosporidium). The results of tests conducted to date show complete removal of the selected microorganisms and surrogates by the POU systems both at startup and after 22 months of operation. The two RO-based POU systems satisfied the Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) requirements for Cryptosporidium removal. The POU devices performed favorably when compared to the reduction requirement of the EPA Guide Standard Protocol for Microbiological Water Purifiers (U.S. EPA, 1987), which is 6 log for bacteria and 4 log for viruses.