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Scientists asked 20 people to wash their hands 20 times each with water that was 15C (59F), 26C (79F) or 38 degrees (100F).
Volunteers were also asked to experiment with different amounts of soap – ranging from 0.5mm to 2mm.
Before they started the tests, their hands were covered in harmless bugs.
Scientists say there was no difference in the amount of bugs removed as the temperature of the water or the amount of soap changed. The temperature does not matter.
Hands should be washed for at least 20 seconds by rubbing hands together in various ways to make sure each surface of each hand is clean. Wet hands and
apply enough soap to cover the whole surface of the hand, rub palms together
with fingers interlaced.
Rub each palm over the back of the other hand with interlaced fingers,
rub between fingers on each hand,
rub backs of fingers (interlocked) and
rub around each thumb, then rub both palms with finger tips and rinse with warm or cold water