The American Society of Microbiology recently presented a study at the 110th General Meeting of the American Society of Microbiology which found that more than 70 percent of bottled water samples from Canada contain bacterial rates more than 100 times the U.S. limit.

Sonish Azam, a participating researcher in the study, commented that, “Despite having the cleanest tap water, a large number of urban Canadians are switching over to bottled water for their daily hydration requirements.  Unsurprisingly, the consumer assumes that since bottled water carries a price tag, it is purer and safer than most tap water.”

Regulatory bodies such as U.S. Food and Drug Administration (FDA), Environmental Protection Agency (EPA) and Health Canada have not set a limit for the heterotrophic bacteria counts in bottled drinking water. However, according to the United States Pharmacopeia, a non-governmental, official public standards-setting authority for prescription and over-the-counter medicines and other healthcare products manufactured or sold in the United States, not more than 500 colony-forming units (cfu) per milliliter should be present in drinking water.

“Heterotrophic bacteria counts in some of the bottles were found to be in revolting figures of 100 times more than the permitted limit,” said Azam.  By comparison, the average microbial count for different tap water samples was 170 cfu/mL.

The study commenced after a Ccrest employee complained about foul taste and sickness after consuming bottled water at the company.

Azam and her colleagues conducted the study by purchasing several different brands of bottled water from local stores and subjecting each sample to microbiological tests.  Results showed that 70 percent of popular brands tested did not meet the United States Pharmacopeia specifications for drinking water.

According to Azam, the bacteria found in the water most likely do not cause disease, and researchers have not confirmed the presence of disease-causing bacteria, although the high levels of bacteria in bottled water could pose a risk for vulnerable populations including pregnant women, infants, immunocompromised patients, and the elderly.

“Bottled water is not expected to be free from microorganisms but the cfu observed in this study is surprisingly very high. Therefore, it is strongly recommended to establish a limit for the heterotrophic bacteria count as well as to identify the nature of microorganisms present in the bottled water,” says Azam.

See the American Society for Microbiology Website for more information.