The build-up in toilets is due to hard water stains. The hard water deposits form a dark ring where the water line rests, because of the calcium and minerals in the water. The unsightly ring can be removed with inexpensive household products instead of purchasing a harsh chemical cleaner. After you remove the build-up in the toilet, you will need to implement a schedule to clean the toilet bowl regularly to prevent it from returning.
Turn the water valve to the off position at the base of the toilet. Flush the toilet so the water level drops below the build-up.
Wear gloves to protect your hands from germs. Lift the toilet seat. Sprinkle baking soda over the build-up.
Fill a spray bottle with white distilled vinegar. Spray the vinegar over the baking soda. Allow the solution to sit on the build-up for 10 minutes.
Scrub the build-up ring with a toilet brush Spray more vinegar over the build-up, and allow it to sit for 15 minutes.
Scrub the mineral build-up again. Repeat adding backing soda and spraying the area with vinegar. Continue to scrub the area until you remove all the build-up.
Turn the water back on to the toilet. Flush the toilet to rinse it.