Bacteriological quality of bottled water brands in Karachi, Pakistan

In the present study, bacteriological quality of 187 different mineral water bottle brands marketed in Karachi was analyzed from September 2009 to June 2010. All the collected samples were analyzed for the presence of coliform bacteria, fecal coliform bacteria, E. coli, fecal entrococci, P. aeruginosa and total viable plate count (TVPC). Alarmingly, 67 (36%) of these samples did not comply with Pakistan and WHO standard guidelines for drinking water. The majority of the specimens (39 samples) were contaminated with higher TVPC and P. aeruginosa, while many were contaminated with both coliform (20 samples) and fecal coliform bacteria (11 samples). Total heterotrophic bacterial number in 49 samples was higher than even 200 cfu/mL. The presence of coliform bacteria in drinking water suggests the possible presence of pathogenic enteric microorganisms thus unsafe for drinking. The data presented here clearly raise the concerns regarding the quality of drinking mineral water and highlights the danger posed to the public health.