Tap Water versus Bottled Water: A Pilot Study

Rodney McDermott, Ryan Knox

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The aim of this exploratory research and comparative numerical pilot study was to investigate any significant differences in the microbiological content of tap and bottled water through the measurement of risk indicator parameters including Enterococci , Escherichia coli (E. coli ) and colony-forming units (CFUs). This study to investigate storage conditions and compare consumer options of public water supply and bottled water using microbiological limits was carried out for public health research. This was a unique pilot study to Northern Ireland with global relevance due to the increase in the bottled water market and the need to address the lack of consumer awareness regarding storage and microbiological content. No E. coli or Enterococci were found in any of the 31 tap or bottled water samples. Three unrefrigerated bottled water samples exceeded the threshold in Colony Counts 22˚C & 37˚C (degrees Celsius) and failed in line with Drinking Water Directive guidelines. This indicated a link between storage conditions and microbiological quality. No link between prices or microbiological quality was indicated. This research recommends the creation of a regulator for the bottled water industry, the need for clearly labelled microbiological content and daily testing. Water suppliers such as Northern Ireland (NI) Water should promote the quality of tap water. Recommendations are also outlined for consumers. There is no statistically significant difference in the microbiological quality of tap and bottled water in Northern Ireland despite marketing claims.
Original languageEnglish
Article number11
Pages (from-to)1398-1407
Number of pages10
JournalThe Journal of Water Resource and Protection
Issue number11
Publication statusPublished (in print/issue) - 26 Nov 2019


  • Water
  • Tap
  • Bottled
  • Public Health
  • Storage
  • Microbiological
  • Regulation


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