You should change or wash your bath towels about once a week or after three to five uses, ensuring they are hung to dry properly after each use to prevent bacteria buildup. Hand towels should also be washed weekly, while washcloths need more frequent washing, ideally a couple of times a week. If towels become musty, lose absorbency, or show wear like fraying, it's time to replace them completely, which is generally every 2 to 3 years for bath towels and 1 to 2 years for hand towels and washcloths. More frequent changing is recommended in cases of illness, skin conditions, or heavy sweat exposure, like gym towels.