Selecting the right toilet brush is critical. Go for an angled one with stiff bristles, which will do a better job accessing the underside of the rim and inside the trap (the hole in the bottom of the bowl). An old toothbrush also works well for getting under the rim.
It's simply something in the water. Calcium, lime, magnesium and iron, naturally found in hard water, attach to just about every surface they come across. Even if you have filters or water systems in place to soften the water, some of these minerals still slip through.
Use a Pumice Stone for Extra Hard Black Rings
Pumice stones are light volcanic rocks with porous surfaces. They are softer than porcelain but stronger than mineral deposits, making it the perfect solution to eliminate rings. Cleaning toilet rings with a pumice stone might require you some hard scrubbing.
When you're cleaning the toilet bowl, it's crucial that you also clean under the rim. To do this, you can use Lysol® Power Toilet Bowl Cleaner, which both cleans and disinfects your entire toilet and is especially angled to hit your toughest stains directly under the rim.
If you notice a visible black or red ring, you need to clean under the rim of your toilet as soon as possible, according to Eve's House Cleaning. To give your toilet rim a good deep clean, apply bleach or vinegar to the stain, and then use a toothbrush or cleaning brush to scrub away the germs and build-up.
Mold comes in a lot of colors. Black toilet mold is the most common color that forms a “ring” in your toilet. This ring can also be from green mold or grey mold. Orange or pinkish slimy mold can develop around the toilet bowl at the spot where the top of the water sits in the bowl.
The color is coming from a black bacteria, mold or sewage. The only way to fix this is to pull the toilet off the floor, remove the toilet's wax ring and replace it with a new wax ring gasket. I would also suggest making sure the drain line is cleared under the toilet – as long as you have it off the floor.
That black substance that keeps seeping into your sink or toilet is usually bacteria that's clinging to waste in your drain lines. This bacteria tends to grow and spread over time, particularly because the matter that goes down these drains is organic in nature, providing a food source for the bacteria to live on.
The staining on the bottom of the bowl is from the minerals settling, and for the toilet ring problem, the water evaporates, the minerals buildup, and when it dries it picks up dirt particles and creates the ring.
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. Simply spray on the affected area, wait a minute or two and brush it away with a regular toilet brush.
Duck® Foaming Bleach Gel better reaches under the rim to get your toilet bowl clean—and it leaves the bowl white and bright.
According to Forté, vinegar is best for removing hard water stains. First, drain the water out of your toilet bowl. Pour enough cups of white vinegar into the bowl, making sure it reaches and covers the entire rim and the water line, "so the vinegar dissolves the minerals that build up there," Forté notes.
"The biggest don't when it comes to toilet tanks is bleach—do not use bleach or products containing bleach inside the tank, as it can corrode the internal parts of your toilet. If you are aiming to remove tough stains from the tank, I also recommend white vinegar diluted with water."
Get your scrubber and vinegar (in a spray bottle, preferably). Spray or pour distilled vinegar inside the bowl and allow it to sit for a minute. Scrub the ring of black mold with a brush or scraper until it comes off. Repeat steps 2 and 3 a few times to remove the ring of black mold, as well as any other spots of mold.
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.
Vinegar will not damage your toilet in any way if it's left in your toilet overnight. In some cases, leaving the vinegar in your toilet overnight is recommended to get the best cleaning results. No matter what material your toilet is made from, the vinegar will not damage your toilet.
Steel wool scrub
Since steel wool is such an abrasive product, you can either use it alone or in addition to borax + vinegar +/or baking soda for better results. 0000-grade steel wool is recommended as it's less likely to scratch up the inside of a porcelain toilet.
Don't leave CLR for longer than two minutes.
Again, CLR is acidic, which makes it effective, but also means it can cause damage if left in contact with surfaces for too long. Always rinse away with cool water after two minutes of contact.