You might have what you need to clean hard water deposits right in your pantry. You can remove lime scale with white vinegar or a lemon (just cut it in half and rub it on the stain). If the stain is covered by layers of soap scum, it may require a lot of elbow grease or something stronger.
The North Carolina Cooperative Extension Office offers a few more suggestions:
- Make a paste of white vinegar and baking soda, let it sit and then rinse.
- Mix 2-4 tablespoons of trisodium phosphate (okay, you might have to buy this one) in a gallon of water, scrub and rinse well.
The second recipe is also good for rust stains. Vinegar is commonly used to get stains out of coffee machines and can even be put into the rinse cycle compartment of a dishwasher to help eliminate and prevent spots on dishes. Don't use acids on marble or granite, as they can etch the surface of natural stone.