What Causes Gray Stains In A Toilet Bowl?

Unlike yellow stains, gray stains aren’t due to your bad sanitary habits or negligence. However, a discolored toilet with gray stains doesn’t look any better. So, what causes gray stains in a toilet bowl, and how can you prevent and clean these stains yourself? This article will help you discover answers to these questions and show you how to keep your toilet good as new!

Mineral buildup, microorganisms, and abrasive cleaners can cause gray stains in a toilet bowl. Gray stains can indicate damage to the toilet due to the reasons listed before. You can use methods like vinegar and baking soda mix, pumice stones, and bleach to remove them.

Gray stains or toilet bowl rings aren’t exactly your fault because they’re mainly caused by mineral buildup and bacteria. However, that doesn’t change that they look bad and are prone to return even if they are cleaned up thoroughly. Let’s look at some ways in which you can effectively clean up these stains and prevent them from coming back:

What Causes Gray Stains In a Toilet Bowl?

Here are a few reasons why you’re seeing those recurring gray stains in your toilet bowl

Hard Water & Mineral Buildup

Are you observing a recurring gray or any other colored ring appear in your toilet bowl? You probably have a hard water situation at hand. Hard water contains minerals like calcium which creates stains of a gray or whitish tone.

Other minerals like magnesium can also cause gray or blackish streaks in the toilet. You can scrub these stains away as soon as you see them, but a more permanent solution is to use a water softener or a filtration system.

clean toilet using wipe and liquid cleaner

Harsh Chemicals & Abrasive Cleaners

Harsh cleaners can contain abrasive materials like chlorine and bleach. These should not be used for regular cleaning. They should be used only when necessary and for the hardest of stains only.

Stains and discoloration caused by these cleaners can become permanent and difficult to clean later on.

Bacteria & Microorganisms

Microbes thrive in moist conditions, and what better place for this than your bathroom? These microbes include everything from invisible bacteria to mold and fungi.

Microbes like to form a circle around the water in your toilet bowl, and that’s why you see a gray ring around the toilet. If it’s moldy, then you will see a greenish tinge to the ring, which will grow darker if you leave it untreated.

How to Get Rid of Gray Stains in a Toilet Bowl?

We understand the agony you go through when these gray stains resurface, no matter how much you clean them. Regardless, you have to clean them. We’ve curated a list of methods that can effectively eliminate these stains for you.

Pro tip: It’s best to empty the toilet bowl before you execute any of the cleaning methods below. This will make your cleaning a whole lot easier.

Method 1 – Bleach Powder

Even the most stubborn stains stand no chance against bleach. It is a part of most industrial cleaners out there, and for a good reason. To clean the gray stains on your toilet with bleach, you’ll need:

  • Bleach powder or liquid
  • Scrubbing brush
  • Soft cloths


  • Scrub the inner side of the bowl with a brush to get rid of the additional residue. Mineral deposits can accumulate around the rim of the toilet.
  • Add ½ cup of bleach to the bowl and let this sit.
  • Take 1 part bleach and nine parts water. Soak the soft clothes in this solution and pack these around the rim. Allow them to sit for 10 minutes.
  • Use the solution to clean up the outside of your toilet bowl and rim area.
  • Take the clothes out of the rim and do a final scrub with a toilet scrubbing brush.
  • Finally, flush the toilet.
vinegar and baking soda in two bottles

Method 2 – Baking Soda & Vinegar

Probably two of the most accessible materials. Vinegar and baking soda can form a fizzing reaction that can get rid of most stains, including gray stains in the toilet. Here’s what you’ll need:

  • Baking soda
  • Lemon juice
  • Vinegar
  • Toilet scrubbing brush


  • Pour a few cups of vinegar with baking soda into the bowl and scrub the mixture around the toilet
  • Let this sit for 15 – 20 minutes
  • After 15 minutes – scrub away at the stains
  • If you still see stains after scrubbing, add some lemon juice to remove them
  • Flush and re-do the process if more cleaning is needed.
person using pumice stone to clean toilet
Image from Niren Joy Riño Yntig

Method 3 – Pumice Stones

If all else fails, you can fall back on pumice stones. All you need here is pumice stones, and you’ll need to scrub away at the stains with these stones. Be careful with sensitive toilet materials other than porcelain, as excessive use of these stones can damage the bowl.

How to Prevent Gray Stains in the Toilet Bowl

Going through such rigorous cleaning routines due to recurring stains can be quite a hassle. It’s best if you adopt some best practices to keep your toilet bowl clean:

young girl scrubbing the toilet bowl
Image from Carrie Clean
  • Use a vinegar spray in your toilet at least once a week
  • Scrub the toilet properly and clean during the week to ensure hard water stains don’t get enough time to accumulate
  • Have a plumber look at your pipes to determine the cause behind frequent staining

Frequently Asked Questions

1. Is it easy to remove toilet bowl stains?

The best thing is that stains in the toilet bowl can be easily cleaned. However, it’s never a best practice to let the stains sit for long periods. You should use traditional cleaning methods or a powerful toilet cleaner to keep the bowl regularly.

     2. Why do stains keep reappearing in my toilet bowl?

These kinds of stains are caused by hard water. Hard water contains traces of harsh minerals like calcium and magnesium. These can keep depositing around the rim of the toilet with every flush and cause stubborn stains. Have a plumber inspect your plumbing because hard water can also clog your pipes and cause major blockages. It’s recommended you use a filtration system to battle this issue.

mold, black sediments in toilet bowl
Image from Skoonmaak Wenke en Idees

    3. What are black sediments in the toilet bowl?

Black sediments in the toilet bowl are indicative of mold and mildew. The black deposits are spores that are being transported through the water holes in the rims of the toilet. These are extremely dangerous for your health. It would help if you had a plumber look at the pipes and remedy this issue before it spreads.

Final Thoughts

Gray stains can be stubborn; they can recur and are annoying in general to clean. Your best bet is to regularly clean the toilet bowl and use one of our recommended methods to keep your toilet bowl spotless!

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