A study of the bacteriological quality of bottled and tap water in Cebu City, Philippines : a thesis presented in partial fulfilment of the requirements for the degree of Master of Environmental Management at Massey University, Manawatu, New Zealand
A study was conducted in the mega urban centre of Cebu City, Philippines between July and October 2013, with the aim of assessing the bacteriological quality of bottled and tap drinking waters. The study was performed during the warm, rainy season, when prevalence of diarrhoea linked to bacterial contamination of water supply is usually at its highest level in tropical countries. The bacteriological tests performed on the water samples were: isolation of E. coli, thermotolerant coliforms, total coliforms, and heterotrophic plate counts. In addition, sanitation programs applied by bottled water manufacturers and the local water system supplier were surveyed by means of a questionnaire. The study focussed on bottled water brands with the greatest combined market share in the study area, and the household taps surveyed were located in villages with the greatest number of local water supply concessionaires.
The results indicated the presence of bacteria in both bottled and tap water samples. A considerable number of bottled water samples from one brand were positive for heterotrophic plate count bacteria. On the other hand, positive tap water samples collected from one household were positive for E. coli, thermotolerant coliforms, total coliforms, and the HPC bacteria. Multivariable Poisson regression modelling indicated a significant variability in heterotrophic bacterial counts between production batches of bottled water. For the tap water samples, statistical analysis was not indicated because all contaminated samples belonged to a single household tap and were collected on one sampling occasion.
In regard to sanitation programs, the municipal water supplier and all except one bottled water manufacturer reported the application of Good Manufacturing Practice and Quality Control programs in the production plant. Interestingly, the only bottled water manufacturer which did not respond to the survey questionnaire manufactured the only brand consistently showing positive bacterial counts and failing the Philippine regulatory standards. It is concluded that a number of factors associated with bacterial contamination in the study area require close monitoring by bottled water manufacturers, water suppliers, and health authorities.