Calcium carbonate is the main culprit—it’s what happens when hard water evaporates and leaves its mineral skeleton behind. Think of it as the fossil record of your tap water, but way less interesting to look at. The good news? It’s alkaline, which means it crumbles when it meets an acid. Enter your new best friends: white vinegar, lemon juice, or even citric acid powder (the stuff that makes candy sour).
Fun fact: In ancient Rome, they used vinegar to dissolve calcium deposits from aqueducts. You’re basically using a technique that’s older than the Colosseum—and way less destructive. So channel your inner gladiator, but keep the battles small.
