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the ineffectiveness of different cleaning behaviors. First,
it may have been caused by limitations of a self-report
questionnaire. Participants may over or under-report
their performance, either because they cannot remember
clearly or because they wish to present themselves in a
socially acceptable manner, which is referred to as social
desirability bias (20). Another limitation of the selfreport questionnaire is the unequal sample sizes between
variables that the questionnaire is assumed to measure.
For instance, only 17 respondents reported that he/she
used the dishwasher to clean bottles, while 34 reported
that they wash with soapy water. Such unequal sample
sizes may potentially affect the validity of analysis. This
might be an area for further research with a larger sample
size. Lack of significance may also have been caused by other
factors, for instance, the cleaning methods that people adopted
may have been insufficient to reduce contamination to safe
levels. Bacteria are naturally present in drinking water and can
reproduce in the presence of nutrients in saliva and backwash
(3, 10). Significant bacterial growth has been shown to occur
in treated, chlorinated water left at room temperature (17, 30).
It is possible that cleaning the day before may not be adequate
to result in a low bacterial count. Reusable water bottles need
to be thoroughly sanitized to reduce the number of harmful
microorganisms to safe levels. Many residential dishwashers have
sanitization cycles that achieve this goal (29). Future studies
may wish to sample the water bottles after cleaning procedures
have been performed. Emptying out the contents and rinsing/
washing the bottle each time before refilling could also be a
suggestion and an area for further research.

In conclusion, although reusable water bottles offer
a green and healthful way to drink more water without
increasing landfill waste, improperly cleaned water bottles
may present a potential reservoir for bacterial colonization
and thus be a risk for foodborne illness. Safe use of reusable
water bottles should include cleaning that effectively
removes all residues and disinfects the bottles on a regular
basis. For water bottles that are not dishwasher safe, or
for residential dishwashers that do not have sanitization
cycles, future studies should determine "best practices" for
effectively cleaning and sanitizing water bottles in a home
environment with minimal special tools or procedures, in
order to maximize user adoption.
Significant levels of contamination were clearly evident
for ATP, HPC, and coliform tests in this study and should
be a cause for concern. In addition, one of the most
interesting results of this study was that use of water bottles
for other beverages results in significantly higher levels of
contamination. Apparently, water bottles are actually very
well-named, and they should be used only for water.
ACKNOWLEDGMENTS
The authors thank Munaz Muntasir, Aaron Camacho,
Daniel Parrinello, Eric Budge and Zach Geurin from NSF
International Microbiology Laboratory for their technical
assistance and microbiological testing. The authors also
thank the Arthur Avery Foodservice Research Laboratory
for its support during this project.

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Table of Contents for the Digital Edition of Food Protection Trends - November/December 2017