Hard water is common in many homes in the U.S. Hard water contains calcium and magnesium and these minerals create a buildup on bathroom tile and fixtures. Frequent standard cleaning is your best defense against hard water deposits. But when you have a tough buildup, you may have to resort to special methods. You can try commercial products, or make your own cleaning solutions at home.
Try a micro-abrasive cleaner such as Bon Ami or Barkeeper's Friend. Sprinkle the surface with the powder cleanser, then rub the stain gently with a damp cloth or sponge. Rinse clean with water and hand dry.
If the stain is resistant, you can make a paste with the powder and small amount of water. Leave the paste on the stain for 15 minutes, then rub gently with a damp cloth. Rinse clean with water and hand dry.
Try natural acids. Apply lemon juice or pure white vinegar directly to the stain and leave for an hour or more. Rinse with water and hand dry.
Try making a paste of white vinegar and baking soda. Apply the paste to the stain and let it sit for an hour or more. When the paste is dry, remove it with water and hand dry immediately.
If the stain is stubborn, you can use either of the methods in steps 3 or 4 repeatedly until the stain is clean, with no risk of harming the tile.
Try a heavy-duty commercial cleanser if these less-abrasive methods don't work. Products such as Lime-Away and CLR are made specifically to break down mineral and calcium deposits and are also safe on tile.