"James Wilkinson Sword" wrote in message
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Never used hot water to wash my hands, always used the cold tap. Just why
do you need hot water for 5% of your body for 10 seconds?

Because cold water is cold water no matter how small a part of the body it
touches or for how short a time - it's still bloody cold if the temperature
outside is below freezing (as it would be for this thread to be relevant)
and therefore the water coming out of the tap is probably not much warmer
(maybe 4-8 deg C).