Battle soap scum with baking-soda paste! By mixing baking soda and all-natural dish soap, you can create an amazing scum-busting paste that rivals any store-bought bathroom scrub. The paste works wonders at removing soap scum from shower doors, as well as hard water and rust stains on ceramic tile. Use a sponge or cloth to rub the paste into the surface until stains are gone, then wipe clean with warm water. To tackle stains on the grout, scrub the area with a toothbrush using the same paste. The paste can be somewhat abrasive, so use sparingly on delicate surfaces.