How often you should wash them: After every wear.
What to know: Salt and chlorine will eat away at a swimsuit and stretch it out prematurely. Hand wash your suit with cool water and a gentle detergent, like Soak ($10 for four ounces, soakwash.com), which deep-cleans and removes that notorious chlorine smell. Allow the suit to air-dry.
Exception to the rule: None. Even if you only dipped a toe in the water, a swimsuit, like underwear, is an intimate garment that absorbs body oils, bacteria, and odors. Best to wash it every time.