Experimental comparison of point-of-use filters for drinking water ultrafiltration

Summary Background Waterborne pathogens such as Pseudomonas spp. and Legionella spp. may persist in hospital water networks despite chemical disinfection. Point-of-use filtration represents a physical control measure that can be applied in high-risk areas to contain the exposure to such pathogens. New technologies have enabled an extension of filters’ lifetimes and have made available faucet hollow-fibre filters for water ultrafiltration. Aim The aim of this study was the comparison of point-of-use filters applied to cold water within their period of validity. Methods Faucet hollow-fibre filters (filter “A”), shower hollow-fibre filters (filter “B”) and faucet membrane filters (filter “C”) were contaminated in two different sets of tests with standard bacterial strains ( Pseudomonas aeruginosa DSM 939 and Brevundimonas diminuta ATCC 19146) and installed at points-of-use. Every day, from each faucet, 100 L of water were flushed. Before and after flushing, 250 ml of water was collected and analyzed for microbiology. Findings Results showed a high capacity of microbial retention from filter “C”; filter “B” released only low Brevundimonas counts; filter “A” showed a poor retention of both microorganisms. Conclusion Hollow-fibre filters did not show a good microorganism retention. All point-of-use filters require an appropriate maintenance of structural parameters to ensure their efficiency.