Q: My three American Standard high-rise toilets installed in 2016 are "behaving" unlike any toilet I have ever had. The low-flush toilets get dirty about once a week, up inside around the rim and above the water line. I constantly have to clean them. I ran a home cleaning company for seven years and have cleaned thousands of toilets, and I lived in a group house of seven people and never had this issue. I have asked plumbers and tried contacting American Standard, to no avail. I really, really dislike having to stay so on top of this problem. There is also a rust-like stain at the very bottom. How do I get that out?

A: It sounds like you have mildew growing around the water line. It may have nothing to do with the toilet design, but may actually be a tip that someone in your house may have undiagnosed diabetes or diabetes that is not under good control. People with diabetes cannot process glucose properly, causing urine to have excess sugar — an ideal food for mildew. Diabetes has serious health consequences, which get worse the longer the disease remains untreated. So your first step might be a call to your doctor’s office.

If blood tests rule out the disease, the need for frequent cleaning could be caused by mineral buildup along the water line or in the holes where water enters the bowl. The rust-like stains at the bottom of the toilet bowl are almost certainly caused by mineral deposits, said Rachelle Fidler, a consumer adviser for American Standard toilets and faucets. Mineral deposits create an uneven surface with lots of crevices for grime to accumulate, and they can clog up the holes where water enters. Once the minerals build up, the deposits are too tenacious to come loose with typical toilet-cleaning tools.

Rubbing with a stick of pumice — a lightweight volcanic rock that resembles a stiff sponge because of all its air pockets — gets rid of stubborn mineral deposits around the water line and at the bottom of the bowl, and a wire can poke through clogged holes.

But pumice should never be used in American Standard toilets made relatively recently, Fidler said. Virtually all of the company’s toilets now have a clear coating, which the company calls EverClean, to make the surface smoother and therefore less likely to become soiled. The coating is fired into the porcelain, which, according to the company, means it can’t rub off. But it can be scratched off with pumice, Fidler said. She wasn’t sure when this coating was introduced, but she said a toilet made in 2016 “most likely has it.”

Instead, the company recommends using chemicals that dissolve mineral deposits. The gentlest approach is to pour in some white vinegar and then add baking soda. The two interact and cause a lot of bubbling that knocks the minerals loose. “It’s kind of like a bomb,” Fidler said, “like when you were in elementary school and made a volcano” by combining baking soda and vinegar in a science project.

If that doesn’t work, American Standard suggests CLR Calcium, Lime & Rust Remover ($5.88 for a 28-ounce bottle at Lowe’s). Never mix this with other cleaners, and pay attention to the instructions on the label about diluting it with an equal amount of warm water before adding it to the toilet bowl. Let it sit for just two minutes — no longer — then rinse.

Fidler said American Standard also recommends muriatic acid to remove mineral stains and deposits from toilets and suggested looking for it in a store that sells swimming pool supplies. But she hasn’t used it herself, and she did not have specific instructions other than to suggest using no more than half a cup. Various websites offer suggestions, but a search for detailed advice from manufacturers of muriatic acid turned up nothing specific about how to use it as a toilet cleaner. A customer service representative for W.M. Barr & Company, which makes the Klean-Strip brand of muriatic acid, said that’s not an oversight. Although the product works great as a way to etch and brighten concrete, she said, “it’s not designed to be used in a toilet.”

Muriatic acid is a variant of hydrochloric acid — not something you want to use without utmost care. The fumes are dangerous to breathe, and the acid burns skin and eyes, which is why goggles, rubber gloves and clothes that cover your skin, as well as excellent ventilation, are absolutely required when working with it. It’s also important to neutralize the acid with baking soda before flushing it down into plumbing pipes.

Given the lack of specifics about how to use muriatic acid, it’s safer to stick to the other options or use toilet bowl cleaners with instructions that manufacturers have vetted.

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