Evaluation of microbiological quality of commercially available bottled drinking water in Colombo district, Sri Lanka

: In recent times, the consumption of bottled water has dramatically increased in Sri Lanka. However, compliance by the producers with the bottled water regulations is debatable, which poses questions about bottled water quality. This study aimed at evaluating the microbiological quality of bottled water in the Colombo district, Sri Lanka. Twenty-six brands of drinking water were collected from the Colombo district (19 locations) microbial quality was detected by checking the total coliforms (TC), fecal coliforms (FC), heterotrophic bacteria, fungi and algae. The results revealed that 50 % of drinking water brands violated the Sri Lanka Standards Institution (SLSI) and WHO guidelines, and the Sri Lanka Health Ministry regulation (0 cfu/100 ml). Twenty-three percent of brands exceeded the limits for presumptive FC (0 cfu/100 ml in accordance with WHO guidelines, SLSI, and the Sri Lanka Health Ministry requirement). Moreover, 35% showed higher heterotrophic bacteria which exceeded the WHO guidelines (50 cfu/ml). The dominant fungi found in the bottled water were Aspergillus spp., Rhizopus sp., Trichoderma sp. and Mucor sp. Chlorella vulgaris was identified as the algal species that was present in the drinking water samples and it was 8 % of the samples checked. Additionally, the statistical analysis of water sources revealed no significant differences in the levels of fecal and total coliforms in samples across springs, tube wells, and dug wells. However, the tube wells have a significant difference in HPC and algae than dug wells and springs. The findings of this study concluded that the bottled water industry needs to be closely supervised by competent authorities to provide customers with more healthy bottled water in Sri Lanka.