In its most basic form, a foot soak is a combination of warm water, salts, herbs, and other skin-loving ingredients. To use a foot soak, one simply soaks their feet in the mixture for about 20 minutes. Foot soaks are typically done to soften skin, soften nails, or soothe sore muscles and joints. Using warm water helps the ingredients properly dissolve, making it easiest to exfoliate the dead skin after the soak.