The brown stain in the bottom of the toilet bowl comes from hard water, which is water that contains a high concentration of minerals. The minerals include calcium compounds, but the ones most responsible for brown stains are iron and manganese compounds. Iron oxide, or rust, is the main culprit.
You can dissolve rust with acid, but it obviously has to be one that is safe for you and for the plumbing pipes. You can also scrub the stains, but you have to be careful not to scratch the porcelain, or you'll end up with permanent stains that you can't remove. The best approach is to scrub carefully with an acidic cleaner.
Using an Acidic Toilet Stain Remover
Acids dissolve rust, and stronger acids work faster than weaker ones. However, no one is suggesting pouring hydrochloric acid or muriatic acid into your toilet bowl. That's dangerous for you and your plumbing. Vinegar is acidic, and it will do the job given enough working time.
Go ahead and pour a half gallon of white vinegar into the bowl to handle stains at the bottom. To treat rings and stains near the rim, make a paste with vinegar and borax or salt and spread it liberally. Leave it there for the better part of a day, spraying occasionally with vinegar as the paste dries out
This cleaning method may be slow, and you may have to repeat it to get all the discoloration off, but it involves little effort. If you aren't afraid of effort, go ahead and scrub the paste with a hard-bristle brush before you flush.
Scrub With an Acidic Cleaner
Maybe you don't have all day to get rid of your brown toilet bowl ring. In that case, you'll want to do more scrubbing, but here you have to be careful. Implements commonly recommended for cleaning toilet stains, such as pumice stones and coarse steel wool, can do a lot of damage. Be on the safe side and use an abrasive sponge or a fine-grit drywall sanding screen.
Scrubbing won't be really effective unless you also use a cleaning agent. The most effective ones contain a dilute concentration of muriatic acid and are sold under such brand names as The Works Toilet Bowl Cleaner or Zep Acidic Toilet Bowl Cleaner. Do not use a cleaner that contains bleach because bleach will fix the stains and make them harder to remove.
How to Do Away With Mineral Deposits in a Toilet
Rust stains can be stubborn and difficult to remove as you've probably already learned, but you can persuade even the most stubborn stains to loosen their grip with a simple procedure:
- Flush the toilet and then empty the bowl with a sponge or turkey baster assigned exclusively to toilet duty.
- Spread cleaning power liberally on all the rust stains. You can use a commercial product or a mixture of vinegar and borax or salt. Pay special attention to the part of the bowl just under the rim, where the stains tend to be more pronounced.
- Scrub gently but firmly with a sponge, sanding screen, hard-bristle brush or very fine (not coarse) steel wool. Monitor your progress closely, and if it looks like the tool you're scrubbing with is etching the porcelain finish, switch to a less-aggressive one.
- Wash off the cleaning powder with a small amount of water. Continue adding more powder, scrubbing and then flushing occasionally until all the discoloration has been removed.
Flush when you're finished scrubbing. The water will flush away the dirt you've scrubbed off, leaving you with a clean toilet bowl, and you're done.