Mold, mildew, and rust can also buildup on the flushing components, creating bad odors and causing the toilet to malfunction. “For example, if the seal has mold on it it might not seal right after flushing, causing your toilet to run, which means you are wasting money on your water bill,” says Geambasu.

What should I do if rust or corrosion build up in my toilet tank?

No worries, just clean it, says Knoll.

  • Turn off the water and flush to empty the tank.
  • Scrub rust spots with vinegar and a sponge.
  • If the rust is really bad, use a rust remover that’s safe for plumbing.
  • Check the parts inside. If they’re broken, replace them.
  • Got hard water? A water softener can help!

Geambasu also recommends using vinegar and baking soda to clean away rust. “And commercial rust removers work, too, but be aware industrial cleaners may cause even more corrosion if not used properly,” he says.