Bacteria Found in Reused Water Bottles

Reusing water bottles saves money and waste, but is it safe? A University of Calgary study found large quantities of bacteria living inside the refilled water bottles of elementary students. Health experts at the Universities of Wisconsin and Minnesota and microbiology experts at the University of Nebraska Medical Center agree that any bacteria from the hands and mouth can transfer to refilled water bottles and multiply. However, daily cleaning, weekly sanitizing and practicing good hygiene can reduce the amount of harmful bacteria that might be swimming around in your bottle.

Fecal Coliform

• Fecal bacteria was found in 9 percent of elementary students' bottles.

  The University of Calgary study sampled the refilled water bottles of elementary students; of the 68 bottles tested, 9 percent contained fecal coliform, an intestinal and potentially harmful bacteria. The study attributes this to improper hand washing after restroom visits by the students.

Total Coliform

• This same study also tested total coliform levels, the common method for testing bacteria levels in water. The total coliform levels were above the maximum allowed by Canadian Drinking Water Quality Guidelines (CWQG) in 13 percent of 75 bottles. Coliform bacteria is not necessarily harmful, but is an indicator of the potential for the growth of harmful bacteria.

Heterotrophic Bacteria

• High levels of heterotrophic bacteria were found in more than 64 percent of the bottles in the Calgary study. Testing for heterotrophic bacteria, bacteria that feed on other living organisms, is done to find the overall water quality. High levels of heterotrophs suggest a high level of bacterial growth.

Other Bacteria

• Any bacteria on the hands and mouth can transfer to water bottles.

  Any bacteria on the hands and mouth will transfer to the water bottle with each use, as Dr. Pete Iwen, a microbiologist at the University of Nebraska Medical Center, describes in an article on this subject. The potential exists for contamination from E. coli and any other number of bacteria, and viruses including the norovirus--whatever the user has come in contact with. Even the saliva from a healthy person can be bad, as it serves to feed harmful bacteria.