Assessment of microbiological and chemical quality of five liter volume bottled drinking water

Abstract

Consumption of bottled drinking water has dramatically increased among the community in recent years worldwide and also in Sri Lanka. The objective of this study was to assess microbiological and chemical quality of five liter volume bottled water during the shelf life period. Three five liter bottles each of three brands were collected for analysis. Microbiological and chemical analyses were carried out monthly after the date of manufacture throughout the first three months of the shelf life of the bottled water. The results indicated that Total Coliform [TC] and Faecal Coliform [FC] counts decreased with time over the first three months of shelf life. There were no significant differences (P > 0.05) in TC between the numbers of microorganisms initially present, with an average count of 107.19 cfu per 100 ml and those present after three months of storage, which decreased to 33.70 cfu per 100 ml, while the level permitted by SLSI for TC is zero cfu per 100 ml. According to national and international standards, the FC count should be zero per 100 ml for drinking water. However, bottled water samples tested exceeded this limit for presumptive FC, with an average count of 0.63 cfu per 100 ml, which declined to 0.3 cfu per 100 ml after three months, without exhibiting a significant difference (P > 0.05). Chemical parameters were within the permitted levels, except pH and hardness in water samples. Therefore, bottled water available for sale needs to be monitored continuously by relevant authorities, in order to provide safe bottled drinking water to consumers.