Water Temp Doesn't Factor into Handwashing Effectiveness, Say Researchers

The study compared handwashing in 60-, 79- or 100-degree water temperatures
The study compared handwashing in 60-, 79- or 100-degree water temperatures

A study conducted by Rutgers University-New Brunswick researchers found that washing hands in cool water is as effective as washing in hot water to remove harmful bacteria. Findings from the study are published in the Journal of Food Protection.

For the study (n=21), high levels of a harmless bacteria were put on the hands of participants multiple times over a 6-month period before handwashing in 60º F, 79º F, or 100º F water temperatures using 0.5mL, 1mL, or 2mL of soap. The data showed no difference between the volume of soap used but the authors stated that more research is needed to better understand the type and amount of soap required to remove harmful bacteria. 

Currently, the Food and Drug Administration (FDA) recommends that plumbing systems at food establishments and restaurants provide water at 100º F for washing hands. Professor Donald Schaffner stated, "...as far as effectiveness, this study shows us that temperature of the water used didn't matter." The authors found that even washing hands for 10 seconds significantly cleared bacteria from the hands.

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Findings from the study may have major implications with regards to saving water energy, as warm or hot water requires more energy than cold water. Professor Schaffner added that rather than requiring a specific temperature for handwashing, "the policy should only say that comfortable or warm water needs to be delivered."

For more information visit Rutgers.edu.