Hot water helps in the formation and suspension of the emulsion. Other additives are sometimes added to soap for antibacterial or antifungal effects, but these are not the main ingredients -- they just enhance the primary function of emulsifying oils in water. See the Web Links for more information and pictures of soap molecules interacting with oil and water. How hand soap works. Soap alone cannot remove dirt or kill germs-- it is the act of running water along with the oils in the soap that help loosen the dirt and rinse it off of your skin. Soap will not destroy the dirt or even germs but the ingredients in soaps such as lye, will make a hostile environment where germs cannot survive.