How to Remove Rusty Scale From Your Toilet Bowl

If you have hard water, your toilet bowl will develop ugly mineral scale deposits. When these are brown, they’re called “rust” stains, but it’s not rust.

These three techniques to clean out the bowl are easy, and two of them are pretty safe. The last is dangerous, but fast.

For all these methods, you need an old toothbrush, and a toilet bowl brush.

Method 1 – Lime A Way

This method takes a couple weeks of effort.

Every night, before going to bed, put around 1/8 of a cup of limescale remover into the bowl. This is around “1 shot” of the chemical.

Every morning, using the toilet bowl brush or toothbrush, scrub at the scale.

The big brush will work for most of the bowl, but you’ll need to use a toothbrush to get into the u-bend.

The limescale remover is made of detergent and phosphoric acid, which reacts with the scale deposits, softening it.

Brushing it will release particles of calcium into the water.

After using the toilet, flush it away. (Don’t let your pee sit.)

Repeat this ritual nightly for a couple weeks. You’ll slowly see the deposits scrub away.

Every day, a tiny amount of scale is being released, but the progress adds up over time.

Method 2 – Vinegar and Soap

Like the first method, this process takes a couple weeks.

This is basically the same as the first method, except it uses cheaper chemicals.

Just before going to bed, you add vinegar and soap to the bowl.

Use around 1/8 cup of vinegar.

For the soap, use a liquid soap, and use a very small amount. If you’re using dishwashing liquid, just add one drop.

The purpose of the detergent is cleaning away any greasy film that might be coating the crystals of calcium. That’s all that it does: it’s a surfacant. You need to clean off the grease.

Feces are made of food and oils, which end up combined with the other yucky substances in the “rust” or scale build up.

(It’s not actually rust, but crystalized calcium and other minerals, mixed with feces and urine.)

Method 3 – Muriatic Acid

This is useful for removing scale quickly, and also for remiving the thick ring of calcium around the bowl, above the waterline. It’s also the most dangerous method.

Pool muriatic acid is another name for hydrochloric acid. You can find it in the garden department of a hardware store. It’s sold in two-gallon packs.

Muriatic acid is 3x more acidic than household white vinegar, and it also has more electrons to react with the crystals, so you need very little.

Before using it, you should dilute the acid.

You must also wear safety goggles and latex gloves. Work only in a well ventilated space, because combining this acid with lime scale releases chlorine gas!

Put half a gallon of cold water into a plastic bucket. Add a small amount of acid, around a quarter cup, and stir it up with a plastic brush or spoon. Swish it gently to mix.

Slowly pour the mixture into the bowl. You want to go slow, so the toilet doesn’t start flushing.

Observe if the scale buildup starts to bubble and foam. If it doesn’t, you need to increase the concentration of acid a little bit. Repeat the above process. You don’t need to increase the amount of acid in the mixture.

Let it sit at least half an hour. Open the windows and let the fan run, so the chlorine gas escapes.

Scrub at the deposits with a brush, to remove the softened particles of scale.

To get rid of a ring of lime, you can stuff a rag into the bottom of the bowl, so it won’t drain. When you add the dilute acid solution, the water level will rise, and submerge the ring.

As before, you need to let it sit a while. Brush at the calcium with a brush.

You can read more about this technique at How to Use Muriatic Acid to Clean a Toilet

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Copyright 2023 and John Kawakami