The dermatologist Dr. Dennis Gross did a major study on water and its effect on skin and he found that the heavy metals in tap water can actually ruin the benefits expensive lotions and serums do for skin. Some cities (New York and L.A., for example) have worse water than others (Seattle, for example). While some dermatologists aren't buying his claims, (Patricia Wexler for one), you can fight the drying effects of water on skin by cleansing with cold cream, a practice common with European women.
Acne treatment that you apply to the skin: Most acne treatments are applied to the skin. Your dermatologist may call this topical treatment. There are many topical acne treatments. Some topicals help kill the bacteria. Others work on reducing the oil. The topical medicine may contain a retinoid, prescription-strength benzoyl peroxide, antibiotic, or even salicylic acid. Your dermatologist will determine what you need.