Survival of Escherichia coli K-12 in various types of drinking water

(1) Huntington Beach High School, Huntington Beach, California

Cover photo for Survival of <i>Escherichia coli</i> K-12 in various types of drinking water

For public health, drinking water should be free of bacterial contamination. Consumption of bottled water, especially in low-income countries has increased to avoid contamination. However, bottling, transportation, and handling procedures increase the risk of microbiological contamination, which is especially harmful to immunocompromised individuals. The objective of this research is to identify the fate of bacteria if drinking water becomes contaminated and inform consumers on which water type enables the least bacteria to survive. This research tested bottled mineral water, bottled spring water, and tap water inoculated with the Escherichia coli K-12 strain bacteria from times 0–72 hours. We hypothesized that bottled mineral water would provide the most sufficient conditions for the E. coli to survive. We found that if water becomes contaminated, the conditions offered by the three water types at room temperature allow the E. coli to survive up to three days. At 72 hours, the bottled spring water had the highest average colony forming units (CFUs), with tap and mineral water CFU values statistically lower than spring water but not significantly different from each other. The findings of this research highlight the need of implementing accessible quality drinking water for the underserved population and for the regulation of water sources.

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