Most people believe that using hot water is more effective than warm. Photo / Getty
Most people believe that using hot water is more effective than warm. Photo / Getty
Scientists have poured cold water on the theory that we need to wash our hands with hot water to kill germs.
According the the Daily Mail, a new study has discovered that cool water removes the same amount of harmful bacteria.
Antibacterial soap was no better than normal soap, researchers also found.
But whichever temperature and soap you use, scrub your hands for at least ten seconds is recommended to get rid of harmful food poisoning bacteria, a New Jersey study suggests.
The findings suggest savings could be made on energy bills, the researchers suggest.
"People need to feel comfortable when they are washing their hands but as far as effectiveness, this study shows us that the temperature of the water used didn't matter," said Professor Donald Schaffner from Rutgers University, who conducted the research
"This study may have significant implications towards water energy, since using cold water saves more energy than warm or hot water."
The team tested 21 volunteers who had their hands exposed to harmless bacteria and who washed at various temperatures over a six-month period.
The washed their hands for ten seconds at a time in water at 15.5, 26 and 38°C (60, 79 or 100℉) using varying amounts of soap.
It was found that neither the temperature of the water nor the amount of soap they used made any difference to the amount of germs removed from their hands.
However, warm water does help in the process of washing, according to a food safety adviser for the British Hospitality Association.
Dr Lisa Ackerley said: "Warm water is good as it helps the soap to lather and it's the action of washing soap off which helps to get hands clean.
"But the actual water temp won't kill bacteria as it can't be too hot or it would burn."
Policy changes
Antibacterial soaps were banned in the US last year after claims they do more harm than good. Photo / Getty
In the US, federal guidelines to restaurants and catering outlets is to provide water heated to 38°C.
The Food Standards Agency in the UK just states that they must provide washbasins for cleaning hands must have hot and cold running water, soap and materials for hygienic drying.
The researchers argue it is more important to ensure workers thoroughly wash their hands, no matter at what temperature, before and after preparing food and using restrooms.
Professor Schaffner added: "I think this study indicates that there should be a policy change.
"Instead of having a temperature requirement, the policy should only say that comfortable or warm water needs to be delivered.
