Should you be showering with a filter? What experts — and social media influencers — say about the effects of hard water.

What’s the cause of your dry skin and frizzy, shedding hair? It might be your shower water, according to TikTok. That’s what influencers promoting shower head filters for brands like Jolie and Canopy are claiming in ads that have become unavoidable on social media.

“I can’t believe a showerhead was the cause of my skin acting this bad,” one woman says in a video for Jolie as she shows off her blemishes. She then claims that her hair is “shedding less” and her skin has improved after she replaced her showerhead with one of the brand’s filtered models. Meanwhile, a video for Canopy’s similar product claims that its filtered showerhead prevents hair breakage and promotes hair growth.

Does your showerhead really make a difference? Experts say there may be some truth to these claims.

Dr. Anna Chacon, a Florida dermatologist specializing in medical, surgical and cosmetic dermatology, tells Yahoo Life that it’s a matter of addressing hard water, which is common in many households. She says hard water can damage scalp and skin health over time but can be filtered out to keep hair and skin “in optimal condition.”

But what is hard water, what impact can it have and is a shower filter a necessary fix? Here’s what you need to know.

What is hard water?

Hard water is water that contains “a high mineral content and heavy metals,” most commonly calcium and magnesium, according to Dr. Jeannette Graf, assistant clinical professor of dermatology at Mount Sinai School of Medicine.

The minerals are natural to the water source and depend on geographical location. A reported 85% of American homes have hard water to some degree, with Indianapolis, Las Vegas, Minneapolis and Phoenix topping the list of cities with the hardest water.

How do you know if your home has hard water? Dry, itchy skin and lackluster hair are two signs indicating you do, along with a filmy residue in your shower, on your dishes or even on your hands after washing. There are also ways to have your water tested if you’re unsure.

Unfiltered shower water may also contain chlorine, which is often added as a disinfectant in public water systems.

How does it affect hair and skin?

The presence of calcium and sulfate in hard water can lead to buildup that Graf says can “interfere with the skin barrier,” keeping skin care products from properly penetrating the skin and potentially blocking pores, which can “lead to further breakouts.”

Chacon adds that those minerals can similarly be damaging to your hair. “The minerals found in hard water can leave behind unwanted residue, which has a range of negative impacts,” including preventing a full deep clean of the hair and scalp,” she says. “This coating and exposure to minerals prevents moisture from penetrating the individual strands and can leave hair looking dull and dry. Post shower, it can even impact the overall look and texture of hair in the long term.”

The extent of the damage to hair has been tested through multiple studies. While research done in 2013 suggested that hard water doesn’t interfere with the strength and elasticity of hair, two follow-up studies found that hair treated with hard water may be thinner and more susceptible to breakage. Claims of hair loss have yet to be proven, though Graf says that mineral buildup can “prevent new hair growth.”

Chlorine is another issue that the brands behind showerhead filters claim to address. “Any amount of chlorine in unfiltered water can be enough to strip the skin of its natural oils, thus making it susceptible to sensitivity and irritation,” says Graf. “It can cause flakiness, excess dryness and exacerbate symptoms of existing skin conditions, such as eczema.”

Do you need a showerhead filter?

Possibly, if you aren’t already doing something to tackle hard water at home. A showerhead filter is either a replacement or an attachment to your existing showerhead, which allows for the filtration process that traditional plumbing doesn’t have. Jolie and Canopy, for example, are showerheads that you install directly onto your water pipe. Both have a filter inside that is to be replaced every 90 days.

It’s an alternative to water softeners, which is most often a tank that needs to be installed at the water source to treat the water before it’s dispersed through faucets. A showerhead filter may be more convenient for people who don’t have access to that source, like anyone living in an apartment building. It’s also important to note that there are other (and more affordable) options of showerhead filters outside of the brands popularized by social media.

Graf says that showerhead filters “will remove more and broader impurities and chemicals from water” by neutralizing those substances as the water is coming out. Jolie, for example, likens its filter to that of a Brita, using water pressure to push shower water through the filter, where a combo of KDF-55 and calcium sulfate work to remove chlorine and heavy metals.

“Over time, it can help prevent unwanted buildup in your shower and also in your hair and scalp,” says Chacon. “Changing your filter regularly is important for preventing buildup and making your system last longer and be more effective.”

Showerhead filters (or other alternative) are especially useful for people with skin conditions such as dermatitis and eczema, as they can help them “keep their symptoms at bay,” adds Graf, but she’d recommend them for anyone.

“Everyone can benefit from having a water filter or softener, as it will help with hair growth and keeping your skin clear,” she says.