Q&A / 

Toilet Bowl Cleaner

DEAR TIM: I’m at my wits end with toilet bowl cleaners. My toilet has light and dark stains in the bottom of the bowl as well as up under the rim. I’ve tried the store-bought Clorox toilet bowl cleaner, Vanish toilet bowl cleaner, and even the automatic toilet bowl cleaners. None of them do anything to cut the stains. What’s causing the stains and what, if anything, can I do to get my toilet looking respectable. It’s embarrassing and I’m about ready to rip it out and purchase a new toilet. Help me please. Amy H., Lexington, KY

DEAR AMY: Oh, I’ve been where you’re at. I remember years ago suffering trying to get a cleaner toilet bowl using all the different products at the grocery store as well as every type of brush and scrubbing pad known to man. I have clear memories of wearing rubber gloves and goggles trying to restore a deeply stained toilet in the basement of a past house I owned.

The normal toilet bowl cleaners you get at the grocery often don’t have the power to really clean a toilet. You may need to use muriatic acid. PHOTO CREDIT:  Tim Carter

The normal toilet bowl cleaners you get at the grocery often don’t have the power to really clean a toilet. You may need to use muriatic acid. PHOTO CREDIT: Tim Carter

The good news is that I eventually was successful, but only after I stepped back and thought about some of the things I had learned in my college chemistry and geology lab classes.

Based upon your description of the stains, and your inability to make progress using ordinary cleaning products, I’m convinced you’re a victim of hard water and lime buildup. It’s very common in many areas of the USA, especially those that have minerals in the water supply.

If you have calcium, magnesium and a few other elements in your water, these can create multilayer deposits inside a toilet. Not only can these deposits be unsightly, but they also can significantly impact the performance of the toilet. If your toilet is like several I’ve had, my guess is that you’ve also noticed that the flushing has become sluggish or not as powerful as it once was.

The ugly deposits happen when dirt gets trapped in between layers of hard water deposits in the toilet. This is most common under the rim of the toilet bowl and along the sides of the toilet bowl above the water line. Each time you flush the toilet these areas of the toilet get wet. Once you leave the bathroom, the water evaporates leaving behind an ultra-thin film of minerals. Dirt can easily attach itself to this coarse film. Then the next flush and mineral buildup locks in the stain. Imagine this happening thousands of times over several years worth of flushes.

You can also get a lime layer buildup in the bottom of the toilet bowl that starts to block the syphon-jet hole. It’s very important that this hole is wide open so that the maximum amount of water can enter the toilet bowl as fast as possible to initiate the flush. 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. The fumes are very nasty and the acid can easily cause skin burns and ruin fabrics that it soaks into. However, when this acid contacts lime and other hard-water deposits, it rapidly dissolves them. Once the deposits have been removed, the toilet looks brand new.

I always start the cleaning project by using the standard toilet bowl cleaners to sanitize the bowl. Once this is complete, I rapidly pour five gallons of water into the bowl simulating a flush. This leaves a small amount of water in the bottom of the bowl. Then I slowly pour into the bowl about 12 ounces of muriatic acid.

Be sure you have the bathroom well ventilated, preferably with a window open to exhaust the acid fumes. Wear tight-fitting goggles, rubber gloves, old clothes with long sleeves, etc. so that you have virtually no skin exposed. Carefully use a toilet brush to spread the acid solution under the rim of the bowl. Do this multiple times over a period of 30 minutes.

Let the acid solution work for up to an hour or two. If you have to leave the room always put the toilet lid down to prevent animals from accessing the acid solution. If children are in the house, never leave the toilet alone. Work until the job is finished.

The muriatic acid will absolutely remove the hard water deposits that are trapping the stains. The longer it soaks the less you have to scrub. Never use a metal scrapper, screwdriver, etc. to dislodge any deposits. The acid will do the work for you, it just may take awhile.

Avoid using any abrasive toilet bowl cleaners. These can scratch the smooth glazed surface of the china. If you take your time and slosh the acid around the bowl and twist the brush in all visible areas, the stains and deposits will disappear in time. Depending on the thickness of the deposits, it can take hours for the acid to break them down.

It's best to completely neutralize the muriatic acid before you get rid of it. Some states may not permit you to flush this chemical into a public sewer system. It's also not a great idea to send acid into a septic system. This is why I instructed you to pour the bucket of water into the toilet bowl to start this process. This allows an ample amount of storage space in the toilet bowl so the acid doesn't enter the drain pipe beneath the toilet.

To neutralize muriatic acid, you just add common baking soda. You'll need 5.5 pounds of baking soda for every gallon of acid you've used to clean the toilet. If you only used 12 ounces of acid and got great results, you'll only need to add a little over a half pound of baking soda into the toilet bowl. Let the baking soda work to neutralize the acid for about 30 minutes. Flush the toilet several times when you think your finished. Repeat the process if there are stubborn stains that didn’t come clean the first time using the industrial-strength toilet bowl cleaner.

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33 Responses to Toilet Bowl Cleaner

  1. If I could fill my toilet bowl up all the way I could remove the stains from many many "jets" with the powdered rust remover from my hardware store. I partially filled my bathtub and added the powder and all the stains disappeared. I don't know how to get the toilet filled up more.

    • Betsy, your question requires lots of typing, plus I have some questions for you so I can give you the correct answer(s). I only do pithy answers here in the comment section. If you want to protect the investment you have in your house and not waste time or money *hoping* you make the right decision, you should talk to me on the phone for just 15 minutes. It'll be the best investment you've ever made in your home!

  2. Our water is pretty neutral but we still had the buildup in the bottom of the toilet and sluggish flushing in that toilet. We also have a septic system with some leach field problems. We worked on the leach field to let the old field “rest.” We put a little Stain Solver in the toilet last thing at night and let it sit all night. After a few weeks the toilet flushed well again and the stain was getting smaller. Now we put stain solver in the toilet overnight twice a week for maintenance. The stain is gone, the toilet flushes, and the leach field is dry. I've tried muriatic acid before and really hated it so while it takes longer for results, I prefer Stain Solver.

  3. I have used muriatic acid to remove mineral deposits from our toilets, and yes, it does work. However, I have found another product that works at least as well, and it isn't as dangerous and doesn't emit the acrid fumes that muriatic acid does. It is called "The Works Disinfectant Toilet Cleaner".

  4. Hi Tim,
    Where can I get this product, muriatic acid, for toilet, bathtub and around the faucet areas covered with hard deposits that cannot get rid of.
    Thank you,

  5. I have just finished cleaning my toilet with muriatic acid and it works like a dream. It's wonderful stuff and it is the only thing which works. I have the same problem as Amy, so I know what she is going through. I didn't realize one had use baking soda, so will next time.

  6. I had the same problem as Amy until my neighbor turned me on to a product that works great on hard water stains. It's "LIME BUSTER" from Whink. In comes in a 16oz green bottle. You just squirt it onand then let it sit for a bit (you'll see it working as it foams up on the deposits). I apply a little more just before I use a Scotch pad to scrub with. As long as you don't let the stains build up to much it only takes some light scrubbing after application. It works great on stainless steel sinks too.

  7. I just had to say WOW, does this ever work! Thank you so much for the tip. I've lived in a small town forever and our hard water just made toilets too nasty to look at, no matter how much you scrub and clean. I just had a new one installed last year and it already looked like you dumped a bucket on mud in it and after a 30 minute treatment it looks like new, thank you so much!!! I really enjoy your newsletters!

  8. Haven't been this satisfied with my housecleaning results as I am today after following your muriatic acid instructions to the letter. We have very hard water - and well water - so we don't always flush after every use. Perfect conditions for creating an impossible to clean toilet bowl. I was also happy to read your explanation why I was having this trouble. Thank you so much.

  9. I use pumice stone to remove hard water rings. It takes some elbow grease to work it off, but you eliminate the chemicals. It does not seem to hurt the porcelain. I got the pumice stone at my local hardware store.

    • A pumice stone WILL RUIN the thin glaze on a toilet. You may not notice damage the first time, but after a few uses, you'll notice the glaze is not high gloss, but starting to dull. I'd NEVER EVER use an abrasive cleaner that contains pumice, or a pumice stone, on glazed china of any type.

  10. I have this problem (the clogged siphon jet) and was considering the muriatic acid approach but then read several warnings that muriatic acid can cause damage to porcelain (etching) and is also hard on (can eat away) pipes and other parts of the toilet and plumbing, especially in an older (built in 1958) house.
    Your thoughts?
    Safe or not?

    • KD,

      Did you take chemistry in high school or college? Do you remember what they stored the HCl in on the shelves? It was a clear glass bottle.

      Was it etched? Do you know what the glazing is on toilets and other china? Ultra-thin clear glass.

      This is why you can TRUST the information here at AsktheBuilder.com because everything here at my website is based in fact, science or decades of hands-on experience.

      Those other places that said muriatic acid can do damage are not 100% correct. What's more, you can neutralize the acid in the toilet bowl BEFORE flushing it away. I say so above.

      I urge you to subscribe to my FREE newsletter so you get funny and factual tips each week from me. Stop listening to the other people that aren't giving you the real scoop.

      • Thanks Tim,
        Well high-school chemistry was so long ago I don't recall that glass had been invented yet 😉

        My confusion was not helped by the pieces of acid info I did have still in my head: use of acetic "acid" for photography; using acid to etch glass and ceramics in my crafting endeavors; hydrochloric acid (Hcl, right?) vs muriatic acid; dilution ratios...

        I did note the neutralize recommendation and had baking soda on my shopping list, so I'm going onward with your suggestion.

        Thank you so much for your quick reply.
        I'm on my way to take advantage of the newsletter!

  11. Hello, I would like to know why you are suggesting putting Muriatic Acid into the water system? We may not be drinking from there, but it goes into the ocean at the end and can do a lot of damage. This is not a good idea! Try using a Pumice stone, it's more work but less damage.

  12. Sharron,
    If you follow Tim's instructions in neutralizing the muriatic acid, it is no longer acid and is not harmful to either you water system or the environment. A pumice stone WILL damage the toilet's glazing. This will make it easier to collect deposits and for it to stain.
    KD, the type of acid will determine what things it will react with. Some will damage or etch glass. Muriatic acid isn't one of them.

    • Thanks Ted for clarifying the acid/etch/reaction confusion.
      And thanks for the support on the use of the MA.
      My toilet is 25+ years old and we've already (manually and carefully) poked out as much of the buildup as possible.
      Use of anything to scrape, scratch, gouge, or poke further is not an option--a pumice stone would NOT work in this situation to resurrect the functionality of my toilet.

  13. Tim, can I put muriatic acid in the toilet tank? Mine is pretty stained up and I thought it would help clear out the rim when I flush it.

    • I think the acid might damage the rubber gaskets in the tank if you do that. What I have done to get acid into the channel and the holes under the rim is to pour the acid through a funnel that is long enough to go through the opening at the bottom of the tank (under the flapper) so it doesn't touch any non-porcelain parts in the tank.

  14. Thanks Tim. I've been trying vinegar soaked paper towels to break down the hard water deposits. It works well on the showerhead but doesn't seem to be doing much for the toilets. I think the muriatic acid will do a much better job.

    However, I'm a little confused on the beginning part of the instructions where you add 5 gallons of water to simulate a flush. Do you completely empty the tank and bowl first? It could very well be that I don't fully understand how toilets work but I certainly don't want to overflow the toilet either.

    Thanks for your help!

    • The purpose of pouring the water into the bowl from a bucket is so you don't have to empty the tank or the bowl by any other means. With newer water-saving toilets you likely don't need 5 gallons of water - a couple might be enough - just enough to get the bowl to self-empty and not retain extra water. There will be a little bit of water left way down in the bottom of the bowl as the siphoning action will not suck it completely dry.

  15. May I add that one should also use a respirator when working with acid that close and in a tightly confined area.

    My sister a few years back was using "diluted" muriatic acid to clean/etch the basement floor in order to paint it. This scorched her lungs even using water and a diluted solution of the chemical.

  16. How about the toilet's tile walls. How do i apply this? I can also see the yellow stain on our walls ( hard water / lume deposits)

  17. SUPER DUPER THANKS for this article!!! It solved our toilet bowl problem for decades!!! Yes! Decades! We were at the verge of changing our toilet bowl. i just followed your instructions thanks for the specifics 🙂 i made it sit for 3 hours and when i flushed its 98% gone. We just need to do one more round. Btw, on the baking soda, do u flush as soon as you pour or wait seconds? As it bubbled /foamed almost pouring out of the bowl when i started to flush, i hope i did it right. Thanks again!!

  18. once neutralised with baking/bicarbonate of soda is it safe for the aquatic environment/wukdlife?
    I am very sensitive to chemical smells. Can I just leave it to do it's job?

  19. I have heard after cleaning use a good car wax to prevent this from reoccurring..... use a sponge to get all the water out before waxing?

  20. You guys rock! Moved into an old apt with nasty, and I mean nasty black stains and lime deposits in the toilet bowl. Took the hints, went to Lowe's, bought a gallon of muriatic acid, took precautions, and boom! Toliet sparkling in 5-10 mins. I was at my wit's end too. Now I won't have to be embarrassed about having people over and apologizing up front.

  21. BEST Advice ever! We were going to change the toilet bowl because the plumber said the holes were too small and that's why the flushing was inadequate. Your post made me realize that the holes in the toilet bowl are clogged! Hope acid clears them up.

  22. OMG! This works exactly as described!

    Used this in Hertfordshire, England. The water is VERY hard here.

    Moved into long disused flat with blackened toilet bowls.

    Tried using cola: nothing.

    I used hydrochloric acid, which is supposed to be identical.

    Let the chemical do its work and about 90 later, I used only a toilet brush, and the stains left.

    A few observations: If the deposits are heavy, expect to see some gas vapors coming from the toilet.


    Hold your breath and get into fresh air before you inhale...

    Adding baking soda causes another reaction, foaming. But scrub gently.

    I found that if I had left it longer, it would have dissolved the larger pieces of limescale.

  23. Tim, our toilets are etched at the water line. I can feel the indention with my fingernail. So, is the toilet shot or salvageable? We have a H2O softner and it doesn't seem to help. We have hard city water here in Florida. Thanks, Brian

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