I think it should be fine. Wear a mask, though, the fumes are dangerous.

Think about the waste plumbing that receives this solution. If it's cast iron, then you are greatly shortening it's life dramatically. But then, the inside of all of your supply lines and fixtures is probably pretty bad without treating your water if your water is as bad as you describe. Treating the symptom and not the problem is rarely the solution.

Just make sure to add the acid to the water when diluting.

White vinegar is also useful, even at 'full strength' (around 4-6% IIRC).

'Glacial (anhydrous) acetic acid' used to be readily available for B&W photo developing (diluted to make 'stop' solution).

Well, when I pour half a cup of muriatic acid into the toilet bowl, which has far more water than that, that's what's called "adding acid to water".

I tried vinegar. Doesn't work. Especially when diluted in the way I described above. If I were to use at close to full strength, I'd need to dump a gallon or more of vinegar in my toilet.

The trouble with using any photo chemical is that chemical has purity I really don't care about, and certainly don't want to pay for.

Hi, I dont believe the acid will ruin your tolet. If you leave it in the toilet too long you could etch it. The etching process doesn't add up though. Say you leave the acid in the toilet and it etches it at two hours. If you flush it at a half hour you won't have a hour and a half to use. You will go back to square one.I wold not worry about it. I have used it many times with no problem, I however pour it down the overflow that way I also clear the holes in the rim.
I no longer purcase the acid from Home Depot. They weakened the acid. I get it at True Value
Good Luck Woodbutcher

To the extent that muriatic acid can be used to etch porcelain (it can), one wonders to what extent this etching constitutes "damage". Now, etching is usually done to make coatings stick. But would continued etching actually be harmful to the surface?

Very true about acid concentration that is sold these days. Muriatic acid ain't what it used to be. I think I last got mine at Home Depot because they weakened the stuff that was sold at Lowes. But now HD has caved as well? But it just means you have to use a little more.

"To the extent that muriatic acid can be used to etch porcelain (it can), one wonders to what extent this etching constitutes "damage". Now, etching is usually done to make coatings stick. But would continued etching actually be harmful to the surface? "

The surface is damaged in a controlled manner to increase the actual surfaces area available for the next coating to bond better.

If a slick glossy surface is desired, etching is damage.

If you you are making frosted glass patterns, it might not be.

Porcelain is used n toilets for sanitary reasons.
It provides a glass smooth surface than is easy to clean and cannot harbor bacteria or viruses well.

That's a good point. Etching will make the porcelain less "slick". Not sure if unslickening it is good for sanitary reasons.

FWIW, I see that "Lysol Toilet Bowl Cleaner" (which is a gel that clings to the side) is 9% muriatic acid. So I suspect that's the kind of concentration one is looking for to do it well and safely. Decent store-bought muriatic acid is 30% HCl, so about one part of that in two of water is what should hit the sides of the toilet, I guess.

You'd think that Lysol isn't too keen on damaging toilets.

Strength and exposure time.

9% can probbaly cause damage if you put it on the porcelain and return a week later to remove it.

MSDS says 10-20% HCl.

Here is a link that might be useful: Lysol Toilet Bowl Cleaner

Bob, at a Dallas Lowes, recently suggested a cleaner that really cleaned my tub after I had tried everything else. It says on the ingredients muriatic acid and to only leave on for 2-3 minutes and rinse off. Probably to keep it from etching. I have a hard time remembering so I set the timer. The same ZEP cleaner solution is not sold in CA at Lowes or Depot. A ZEP mold and mildew is sold in CA and it doesn't do the same job.

Well, the blue squirt bottle of Lysol Toilet Bowl Cleaner that I pulled off the shelf at the store today says "ACTIVE INGREDIENT Hydrogen Chloride 9.5%". So I'm not sure what the MSDS that you link to pertains to. It's dated 2009. One wonders if, like the muriatic acid being sold in the store, Lysol started diluting the stuff for "safety".

But Janice, that's probably the key. You leave it on for just a few minutes and then rinse it off. I didn't check to see if that's what the instructions on the Lysol said, but I'll bet it is.

OK, we're closing in on a strategy here.

If you are concerned about damaging the porcelain, get a used toilet at the thrift store and leave your proposed treating solution on it for a few hours or days and see what happens.

Given what happens to all of your other plumbing, and the fact that you need to use huge quantities of detergent in the laundry, bath and kitchen, I think you'd be happy with a water softener.

HCl in the tub will likely take out the drain hardware. I'd remove the strainer first, at the least.

I've never had a problem with my other plumbing, nor do I use huge quantities of detergent. (In fact, I use my wash water as gray water outside, so I try to use rather little. My underwear is clean.) My water doesn't even have much of a taste. But it does, after a few months, leave deposits in the toilet. I'm not retrofitting my house with a water softener to keep my toilet clean!

What strainer? We're taking toilet tub, not bath tub.

I'm just reaching for what Lysol sells to clean toilets. If they sell a 10% HCl product to be used for a few minutes, and don't manage to get themselves sued for destruction of property, it works for me.

Just a quick followup to this. I have discovered that plain, cheap, household vinegar works fine for this. Just takes longer. Drain the tank, empty out the bowl (maybe with a plunger), and put a cup of 5% vinegar in the bowl. Rinse it around the sides. Leave for a few hours. The scale will gradually come off. If the scale is high up on the bowl, saturate some tissue with the vinegar, and layer the tissue on the scale. That just keeps it wet with vinegar.

No more muriatic acid or pricey bowl cleaners for me, nor danger of porcelain etching.

Just a quick followup to this. I have discovered that plain, cheap, household vinegar works fine for this. Just takes longer. Drain the tank, empty out the bowl (maybe with a plunger), and put a cup of 5% vinegar in the bowl. Rinse it around the sides. Leave for a few hours. The scale will gradually come off. If the scale is high up on the bowl, saturate some tissue with the vinegar, and layer the tissue on the scale. That just keeps it wet with vinegar.

No more muriatic acid or pricey bowl cleaners for me, nor danger of porcelain etching.

"Etching will make the porcelain less "slick". Not sure if unslickening it is good for sanitary reasons."

Glad you came up with a solution (vinegar). DH used diluted muriatic acid to clean an old porcelain tub and it destroyed it, ruining its "slickness."

Using 5 pounds of baking soda helps reduce the acidity of the product allowing for safer flushing. The chemistry behind it is that the baking soda neutralizes the acid. This is a great way to help protect your pipes and the environment.

I don't use water any more. Just vinegar. I have a tank of it hooked up to my supply line and only fill the toilets with vinegar. No more calcium buildup! I also use it to do dishes and laundry . Vinegar also cleans all the surfaces of my house, the chandelier and I even put it in our power washer to clean the house. Boy, vinegar sure is great. It's so economical too. very refreshing to shower in and makes a delicious cup of tea. Tomorrow I'm going to fill my car tank with vinegar instead of gas. SO much cheaper ! and then the printer cartridges and my perfume bottles after that!

A reminder to go with the above... Don't mix acid with bleach. It will generate poisonous chlorine gas, along with even worse gases depending on the mixture.

Acids include muriatic acid (also labeled as hydrogen chloride), vinegar, and sodium bisulfate (also labeled as sodium hydrogen sulfate), as well as rust removers like CLR and Lime-A-Way.