Fun fact: There’s a good chance that calcium is building up in your hair and you don’t even know it. The U.S. Geological Survey (USGS) claims that about 85 percent of homes have hard water, meaning it contains higher than normal concentrations of magnesium and calcium ions. Although showering or bathing in hard water doesn’t have serious health consequences, your hair could suffer. Research, including a 2018 study, has found that hard water reduces the strength of hair “therefore leading to hair breakage.”

This is where Kérastase K Première Reparative Shampoo comes in, specially designed to descale your hair.

Kératase K Première Reparative Shampoo, 2.7 oz

No matter what hair type or problems you have, using the right shampoo is essential to the health of your hair, explains Los Angeles-based celebrity hairdresser Sean James, whose A-list clients include Jamie Lee Curtis and Riverdale‘s Cole Sprouse. “Calcium deposits from hard water can make hair dry, brittle and dull by blocking moisture and nutrients,” says James InStyle. Nazanin Saedi, MD, board-certified dermatologist at Dermatology Associates of Plymouth Meeting, adds that hard water “also makes hair more prone to breakage.”

Although everyone has limescale deposits, “people who have hard water in the shower will have more of them,” explains Saedi InStyle. According to James and Saedi, there’s a magic ingredient in the Kérastase K Première hair repair shampoo that reverses the damage hard water can do to your hair. “The citric acid can bind to calcium and help remove it from your hair,” says Saedi. The shampoo also contains glycerin, “which helps to add and retain moisture to your hair.” The combination of the two ingredients “helps restore suppleness and increase moisture absorption, leaving your hair beautiful and shiny,” says James.

Kératase K Première Reparative Shampoo, 8.4 oz

Even though I have a water softener installed at home, hard water has definitely left my hair dull and weak, so I got hold of the line as soon as I could, which includes a shampoo, conditioner, pre-shampoo treatment, hair mask and oil. Before shampooing, I start with the concentrated Première Repairing Pre-Shampoo Treatment, which prepares the hair for the rest of the treatment. After just the first wash with the Première Reparative Shampoo, I noticed an immediate difference; not only was my hair much softer, but it also looked and felt healthier overall.

Kératase K Première repairing pre-shampoo treatment

After washing, there are two options: the Repairing Conditioner or the Anti-Breakage Repairing Mask, both enriched with glycine. The conditioner is fairly lightweight, while the Superpower Mask is a creamier, five-minute treatment for extra nourishment. (I alternate between these depending on how much moisture my hair needs.) There’s also a Repairing Gloss Oil to add a little extra shine and shimmer.

While the price of the full-size Kérastase K Première Reparative Shampoo might be a bit high, the brand offers a travel version for $22 to get you started. I personally found that you don’t need to use the products every time you wash your hair either. I only use it once a week and alternate it with other shampoos and conditioners.

You can shop more of my Kérastase K Première favorites below.

Kératase K Première repairing conditioner

Kératase K Première anti-breakage repair mask

Kératase K Première repairing shine oil