Wet your hands with clean, running water (warm or cold), turn off the tap, and apply soap.
Why? Because hands could become recontaminated if placed in a basin of standing water that has been contaminated through previous use, clean running water should be used 1. However, washing with non-potable water when necessary may still improve health 3. The temperature of the water does not appear to affect microbe removal; however, warmer water may cause more skin irritation and is more environmentally costly