We’ve all been there: You’re about to slip into the bathtub for a relaxing soak after a long day or you’re giving your children a much-needed bath when you start to wonder: “Is the tub actually clean enough to host a human body?” Maybe there’s a ring of residue in the tub, signs of mold or mildew on the tile or grout, pinkish scum on the shower curtain or slimy stuff on the rubber bathmat. You think: “How much of that will get into the water, and could it harm my health?”

Or perhaps you’re facing the flip side: the lingering whiff of pungent cleaning products in a recently cleaned tub. In this case, you may be worried that some of those chemicals could get into the water and onto your skin.

Some of these are legitimate concerns. Research published in a 2004 issue of the journal Applied and Environmental Microbiology found that the soap scum on vinyl shower curtains is “a lush bed of microbes,” mostly bacteria that’s embedded “in a biofilm matrix.” Fungi and mold also can grow in these perpetually moist environments. “About 10 percent of bacteria you find in bathtubs comes from fecal matter, and it can get dried into the bathtub ring,” noted Jason Tetro, a scientific consultant in microbiology and immunology based in Edmonton, Alberta, and the author of “The Germ Files.” But to get sick from E. coli or another infectious form of bacteria, “you would have to drink a lot of bathwater,” Tetro added.

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Aside from the considerable ick factor, experts say that the microbes that hang around bathtubs probably won’t make most people sick. They will become highly diluted once the tub is filled with water, and “even if bacteria is present, the immune system in healthy people will fight it off,” said A. Yasmine Kirkorian, chief of the dermatology division at Children’s National Hospital in D.C. “Right now, we’re emotionally sensitized to anything infectious because of covid-19, but your bathtub is not likely to make you sick.”

For immunocompromised people, it may be another story. If someone has immunosuppression because of an illness or a medication they’re taking, or they have breaks in their skin because of a wound or eczema, there’s a higher risk of developing a bacterial infection, such as folliculitis (inflammation of the hair follicles) or boils on the skin, said Bruce Brod, a clinical professor of dermatology at the University of Pennsylvania School of Medicine.

Those who have asthma or chronic respiratory conditions may be irritated by mold and bacteria in shower heads, faucets, caulking or tile grout, said Ryan Sinclair, an associate professor of environmental microbiology at the School of Public Health at Loma Linda University in California. “You don’t have to be a scientist to identify mold. All you have to do is see black or brown spots and detect a musty, earthy smell. The recipe for growing mold is nutrients from skin cells, moisture and sometimes darkness.”

For most people, however, a bigger health concern is the products they use to clean the bathtub. “You’re more apt to get in trouble from the chemicals [in cleaning products] than the germs that are in the tub,” said Roberta Lucas, a clinical instructor of dermatology at the Dartmouth-Hitchcock medical center in Lebanon, N.H. For one thing, the vapors from strong chemical-based cleaning products can be irritants for those with asthma or respiratory issues.

A good resource is the Environmental Working Group’s website, ewg.org, which has information on which commercial bathroom cleaners contain fewer potentially harmful ingredients.

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“Cleaning agents that have chemicals or fragrances can leave a residue and become part of your bathwater or part of the air you breathe in the bathroom. Hot or warm water volatilizes chemicals that are on the surface, which makes them stronger,” said Marilee Nelson, a Texas-based environmental consultant and co-founder of Branch Basics, a brand of plant- and mineral-based fragrance-free cleaning products.

For another thing, the fragrances and other ingredients in chemical cleaners can cause skin irritation or contact dermatitis in some people. “If you have eczema, which is a skin barrier defect, you’re much more sensitive to irritation from allergens and fragrances” in cleaning and personal-care products, Kirkorian said. In that case, it’s wise to steer clear of cleaners that contain strong chemicals or fragrances — and to avoid bath bombs or bubble baths for the same reason.

This is an area where doing (or using) less may mean more for your health. Here are simple expert-recommended steps you can take using a solution of diluted bleach (1 part bleach to 9 parts water) or a hydrogen-peroxide-based cleaner:

Clean the bathtub once a week. Be sure to have good ventilation and wear gloves. Spray the solution all over the tub, let it sit for a few minutes, then wipe the tub with a clean sponge and rinse it thoroughly with fresh water, Tetro said.

To minimize mold growth on and around tiles: Use a toothbrush with one of these solutions to scrub nooks and crannies. “If you routinely spray the caulk with a nontoxic soap, rinse it off and dry it with a towel,” Nelson said, then you can prevent mold and mildew from building up. “Never use steel wool. It can ruin the tub.” For tough stains, mix 2 parts baking soda paste with 1 part hydrogen peroxide, apply it and let it sit for 30 minutes, then wipe it off and rinse the area, Nelson said.

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To flush out bacteria and mold from the faucet, shower head and drain: Spray on the diluted bleach or hydrogen-peroxide-based cleaner, let it sit for a few minutes, then let clean water flow through it.

For shower curtains: Put them in the washing machine at a high temperature with diluted bleach, Sinclair suggested.

For rubber bathmats: Spray with a gentle solution of soap and water, the hydrogen-peroxide-based cleaner or diluted vinegar, and use a scrub brush to clean it. Rinse it thoroughly and dry it before putting it back in the tub. It would be better to avoid storing mats and other accessories such as bath toys in the tub, Kirkorian said, because repeated immersion in warm water can promote the growth of mold, mildew and bacteria on them.

With regular TLC, your bathtub really can be the healthy, relaxing oasis you want it to be. It’s just a matter of knowing what to do — and what not to.

Stacey Colino is a writer in Chevy Chase, Md., specializing in health and psychology.