Heterotrophic bacteria in botte refill stations

Abstract

Background: Heterotrophic bacteria are commonly found in water supplies where there is inadequate or non-existent disinfection. Water coolers are known to have high HPC levels due to the filtered, non-chlorinated water provided. Water bottle refill stations utilize a carbon filter which can act as a food source for HPC. This study measured HPC levels in water samples from bottle refill stations to determine whether there is a difference compared to tap water at BCIT. Method: Standard Method 9060 A was used to collect water from bottle refill stations to compare to non-filtered tap water. Samples were plated using R2A Agar and incubated for 7 days before enumerating HPC from water samples. Samples were collected from specific drinking water fountains that contained Carbon Filters and compared to the nearest tap water source. Results: Mean HPC levels in bottle refill stations were found at 95 cfu/mL while mean HPC levels in tap water were 55 cfu/mL. A two-sample T-test confirmed that the mean HPC levels of bottle refill stations and tap water are statistically significantly different (P= 0.000124). Although the findings were statistically significant, the study’s power was low at 11%. Conclusion: Based on the results, drinking water obtained from bottle-refill stations at BCIT contained on an average higher level of HPC compared to tap water. Overall, HPC levels were below recommended levels in drinking water and not considered to have any harmful effects. To continue the safe use of bottle refill stations, facilities should develop and follow written procedures to maintain stations and ensure regular changing of filters.