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

Using soap to wash hands is more effective than using water alone because the surfactants in soap lift soil and microbes from skin, and people tend to scrub hands more thoroughly when using soap, which further removes germs

Lathering and scrubbing hands creates friction, which helps lift dirt, grease, and microbes from skin.

Microbes are present on all surfaces of the hand, often in particularly high concentration under the nails, so the entire hand should be scrubbed

Determining the optimal length of time for handwashing is difficult because few studies about the health impacts of altering handwashing times have been done.

The optimal length of time for handwashing is also likely to depend on many factors, including the type and amount of soil on the hands and the setting of the person washing hands.

Accordingly, many countries and global organizations have adopted recommendations to wash hands for about 20 seconds (some recommend an additional 20-30 seconds for drying)

Soap and friction help lift dirt, grease, and microbes—including disease-causing germs—from skin so they can then be rinsed off of hands. Rinsing the soap away also minimizes skin irritation.

Because hands could become recontaminated if rinsed in a basin of standing water that has been contaminated through previous use, clean running water should be used.

Germs can be transferred more easily to and from wet hands; therefore, hands should be dried after washing.

However, the best way to dry hands remains unclear because few studies about hand drying exist, and the results of these studies conflict.

Additionally, most of these studies compare overall concentrations of microbes, not just disease-causing germs, on hands following different hand-drying methods.

Nonetheless, studies suggest that using a clean towel or air drying hands are best.