To investigate the safety of the hospital water supply following a major flood.

Surveillance was conducted of the hospital water supply as it entered the hospital and at randomly selected water faucets throughout the facility.

A newly constructed surgical critical-care unit in a 265-bed community hospital that had to be evacuated and was out of operation for 6 weeks following a major flood of the city.

Random water samples throughout the facility were analyzed for heterotrophic plate counts (HPCs), chlorine, and coliforms utilizing standard methods.

Water samples entering the hospital met appropriate standards, indicating the city water distribution system was not contaminated. Of 169 faucets tested, 13 (22%) of 59 electronic faucets exceeded the HPC threshold, and 12 (11%) of 110 manual faucets exceeded the HPC threshold (P<.14). A comparison of two brands of electronic faucets with manual faucets and with each other revealed that the HPC threshold was exceeded by 11 (32%) of 34 brand A faucets as compared to 12 (11%) of 110 manual faucets (P<.006). The HPC threshold was exceeded by 2 (8%) of 25 brand B faucets compared to 12 (11%) of 110 manual faucets (P<.94). Contamination rates of brand A and brand B faucets differed significantly (P<.003). Similar testing 2 months after hyperchlorination of the water supply indicated that the HPC threshold was exceeded by 16 (52%) of 31 brand A faucets compared to 10 (9.%) of 110 manual faucets (P<.0000003) and by 2 (18%) of 25 brand B faucets compared to 10 (9%) of 110 manual faucets (P=1.0).

A certain brand of electronic water faucet used in the hospital was associated with unacceptable levels of microbial growth in water and was a continuing source of bacteria potentially hazardous to patients.