The best way to clean toilet stains from tough mineral buildup is with lemon juice or any source of citric acid. Spray on the lemon juice and leave it overnight. Then spay on another light layer and wait a few minutes before scrubbing your toilet. Flush to rinse away the stain.
Citric acid
More importantly, it's probably even more effective than vinegar for getting rid of that brown stain in the toilet. Simply pour a kettle of almost boiling water into the bowl, follow up with 250ml of citric acid, and leave it for some hours – preferably overnight. The next day, scrub and flush.
To clean calcium buildup out of your toilet, use vinegar or another acidic cleaner. The acid will break down the mineral deposits so you can brush them away. Be sure to take the necessary safety precautions when working with cleaners. Wear gloves and eyewear and open windows for ventilation.
Vinegar is a natural acid that can dissolve calcium deposits. You can pour vinegar into the toilet bowl and let it sit for a few hours before scrubbing with a toilet brush.
If the clog still seems to be intact, start over at step 1 and repeat the process a couple of times. For extra-stubborn clogs, you can let the fizz mixture sit overnight or combine this method with plunging.
That brown toilet-bowl stain isn't what you think it is
It's actually due to high concentrations of minerals in hard water, like calcium, iron, and manganese, that build up inside the toilet bowl over time, according to Hunker. In particular, iron oxide, or rust, is the main problem.
A much better solution is to use some WD-40 Multi-Use Product. Most people don't know that WD-40 can solve many of their household cleaning needs quickly and easily. When cleaning a toilet bowl, WD-40 works by softening the rust and lime deposits, so they can be easily wiped away. You don't need to use much of it.
Cleaning with a mixture of baking soda and vinegar in the bathroom can work really well. To clean your toilet with vinegar, pour a cup of vinegar in the toilet bowl and let sit overnight. The next morning, sprinkle a little baking soda into the bowl, scrub, and then flush clean.
Let It Sit For 12 Hours
Leave the vinegar and water mixture in the toilet tank for 12 hours without flushing the toilet. This is why this cleaning process is best done overnight, as you are less likely to need the bathroom throughout the night than during the day.
To remove limescale from the bottom of your toilet you will want to pour vinegar into your toilet bowl and leave that on there for three to four hours. After the vinegar sits, you can scrub those stains with either a toilet brush or a wet pumice stone and flush the toilet.
Hydrogen Peroxide and Vinegar
“Combining these two creates peracetic acid or corrosive acid, an irritant that, in high concentrations, can harm the skin, eyes, throat, nose, and lungs,” says Bock.
OxiClean™ Bathroom Cleaner can help you thoroughly clean both the toilet bowl and around the base in an effort to keep scum buildup at bay.
If you want to really get your toilet tank clean, then you need to make sure you have the right cleaning products for the job. Vinegar is a great toilet cleaning solution. Not only is it free of chemicals and naturally antibacterial, it's also an acid, so it will remove minor lime and calcium deposits.
In this case, a basic toilet cleaning product may not be enough, and you will need to use undiluted bleach. As a one-stop cleaning solution, pour one cup of bleach around the bowl. Then tackle every inch with a toilet brush or a handheld scrub brush. Let it sit for five minutes, then flush.
Pour one cup of baking soda into the clogged toilet, and then chase it with the hot water/vinegar mixture. Leave the volcano mix to do its job, checking in about 30 minutes. In most cases the clog will have come apart, and a simple flush with send it all down the drain. Plus your toilet bowl will be cleaner!
Water entering through the rim of the bowl can also be slowed by mineral deposits in the small holes under the rim. The best toilet bowl cleaner I've come across in these situations is muriatic acid. This is a very powerful chemical that should be used with great care and respect.
Use Vinegar & Baking Soda
White vinegar is a natural solution that can be utilized to dissolve calcium buildup. Sitting overnight, you will be able to remove lime buildup from the drain while avoiding the harsh chemicals in traditional drain cleaners. Avoid putting any store-bought chemicals down the drain.