Toilet - lime-like deposits in odd location

Question

Sorry for the disgusting picture.

You can see the lime-like deposits in a line on top of the toilet bowl.

Two questions:

• How did they get there?

• How do I get rid of it? (Note: I use 25% Hydrochloric Acid and/or 25% Phosphoric Acid to get rid of the scum at the bottom of the toilet bowl. It works. But it's easier to use in the bottom of the bowl because the acid just sits there and I can leave it there overnight. But given the location here, on top of the toilet bowl, the acid won't sit there, it'll just slide off).

Note: I do want to mention that according to a janitorial supply store worker I had a conversation with, these deposits are the result of some sort of bacteria (excretion from the bacteria, much like tartar around our teeth). They may or may not be lime or a combination of lime and something else (maybe rust).

Answer 1

Yes, the stains can result from bacterial metabolism, working on the iron and manganese in the water. The Minnesota Department of Health describes that issue in more detail.

So what to do?

• Reducing the amount of minerals, e.g., with an iron-removing water softener, can reduce the amount of oxides deposited. This is an expensive initial investment, and requires maintenance.

• You can try disinfecting the water source with hypochlorites (bleach). This likely would need to be repeated periodically, and excessive disinfectant can make the water unpalatable and reduce life of rubber plumbing parts.

• There are various commercial products similar to the phosphoric acid / hydrochloric acid mix (also containing milder sulfamic acid), such as Iron OUT and Red-B-Gone, that have thickeners, or can be made into a paste, to help the cleaner to adhere to the vertical rim of the toilet.

  Since you already have that acid mix, you might add a thickener, such as propylene glycol, polyethylene oxide (or perhaps a common food thickener, such as guar gum -- though the acids might quickly break that down). Also try applying a bit of paper towel, wetted with the acids, to the stain.

N.B.: Use of phosphoric acid / hydrochloric acid is hazardous, and is suggested only since you stated you've used them already and should be familiar with safety precautions, such as use of a face shield and rubber gloves, and having running water and baking soda available should some acid splash!