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Damaged Hair: The Hidden Perils Of Hard Water

Water - and more specifically the calcium within - can cause damage to your hair.
The secret to defending your hair fibers? Decalcification.
Discover all there is to know to keep your locks strong, shiny and supple.

Hard water, with its high calcium content, can cause hair breakage especially if it's already damaged, bleached, or processed. Often underestimated for its potential harm, hard water can be a silent assailant to your strands, weakening and dulling them.​ ​

The key to saving your hair fibers from this hard water is hair decalcification. In this article, we’ll dive into the science behind why hard water is detrimental to your hair and the practical tips you need - including how to decalcify – in order to protect your hair from the perils of hard water.

Why Water Damages
Your Hair?

Water is life, and it plays a crucial role in maintaining our overall well-being. However, when it comes to your hair, the type of water you expose it to can either be a blessing or a curse. Hard water is water that is rich in minerals, predominantly calcium and magnesium.​ ​

When we think of hard water, we often think about limescale - that chalky deposit that builds-up around taps and in the depths of your kettle - but when it comes to hair, it’s the calcium that is the real issue. Strange, right? Because when we think of calcium, we often link it to strong, healthy bones and teeth but when it comes to hair, calcium buildup is not your friend - it can, in fact, lead to a range of problems, including hair weakening and breakage.

What Type of Damage Can Calcium
Cause to Your Hair?

Now that we know why calcium is good for our bodies but bad for our hair when exposed regularly,​
here are 3 types of damage that calcium can cause to your hair:


Calcium reacts with the proteins in your hair fibers causing them to stiffen. This stiffness can make your hair feel coarse and difficult to manage, leading to more breakage during styling or brushing.


Calcium can form a coating on your hair, making it look dull and lacking luster. This layer can prevent moisture on the hair shaft, leaving it dry and lifeless.


Calcium can weaken the protein structure of your hair, making it more prone to breakage. This is especially concerning for those with already damaged or porous hair, as it exacerbates the problem.​

How to Decalcify your Hair and
Protect it from
Hard Water?​

Hair decalcification is the process of removing the damaging calcium buildup from your hair. This procedure is essential for maintaining healthy, lustrous hair, particularly if you live in an area with hard water.​

There are several methods for hair decalcification, including specialized shampoos, conditioners, and treatments designed to dissolve and remove excess calcium. Regular use of these products can help restore the natural balance of your hair and prevent further damage.

These Products
Could be for You!

To keep your hair looking its best, implement hair decalcification into your routine and use products designed to combat the impact of hard water on your hair.
With the right routine and a little extra attention, you can keep your hair strong and healthy, even in areas with notoriously hard water.

What Products to Use
to Avoid Hard Water Damages?

Did you know, damaged hair absorbs
3x more calcium than healthy hair?

That’s where the new hair strengthening range, Première, comes in, as it has been specifically formulated to decalcify your hair fibers using citric acid and glycine – giving your hair a mineral detox.

The Kérastase Première Decalcifying Repairing Pre-Shampoo Treatment contains 3% citric acid known to eliminate the calcium buildup, neutralising dullness and stiffness. Added to that is 5% glycine, an amino acid, known to penetrate the hair to reconnect broken keratin links (caused by the calcium) to reduce breakage. The dual action repair, both outer and inner repair, can restore hair's original strength* 

Sounds too good to be true - we know - but it’s not magic, it’s science. Find out how the Kérastase Decalcifying Repairing Pre-Shampoo Treatment traps and eliminates the excess calcium with this experiment done by Edine Ahbich, Kérastase Scientific Director.​

At-Home Decalcification Ritual

The key to the Première range is the power of layering (a hot new hair trend, you can read more about hair layering here)
to remove the calcium deposits from the outside and inside of your hair fiber.
By layering our powerful Première clarifying pre-shampoo treatment with the shampoo, the active ingredients are able
to penetrate the different layers of your hair for optimal decalcification and mineral detox.


Start with the Kérastase Première Decalcifying Repairing Pre-Shampoo Treatment, a pre-shampoo concentrate that is the clarifying hero of the collection. Use on slightly wet/damp hair and should not be rinsed before applying the shampoo (layer 2).​ ​

With 3% citric acid and 5% glycine, it decalcifies your hair helping reverse stiffness and dullness, restoring hair's original strength* and increasing shine by 75%*.​


Our Kérastase Première Decalcifying Repairing Shampoo should be applied directly on top of the Concentré (you can add a little water to emulsify, if needed).​ ​

Its creamy texture and voluptuous foam gently cleanses away calcium overload and helps neutralise dullness and breakage. Hair is left feeling healthier.


Once hair is towel-dried you can layer on the Kérastase Première Anti-rigidity Decalcifying Repairing Conditioner, or the Anti-breakage Repairing Filler Mask.​

The lightweight formula of the conditioner quickly gets to work to restore moisture and fluidity. In fact, hair is left up to 7 x smoother*, up to 82% shinier* and up to 2x* softer.​ ​
The rich, creamy mask should be left on towel-dried hair for 5 minutes in order to penetrate fibers.


Calcium doesn’t just cause breakage, it enhances damage and dryness leading to frizz, so our Kérastase Première Repairing Anti-frizz Filler Serum is designed to repel humidity and protect against heat up to 230 degrees*.​ ​

Intensive Shine Repairing Oil is a nourishing oil that seals the look of spit ends and boosts shine by up to 4x*. It’s the perfect addition to polish hair after heat styling or to tame flyaways if you tend to leave you hair to air dry.

In-Salon Decalcification Ritual

For the ultimate hair decalcification in salon, your hairdresser can offer our salon-exclusive clarifying Concentré Liquide Resurfaçant.​ ​

After your hairdresser layers the Pre-Shampoo with the Shampoo, they will rinse. Then they will apply the Kérastase Decalcifying Resurfacing Concentrate with the Mask, before rinsing again.​ ​​

This double layering technique offers the highest exposure to citric acid and glycine in one hit to intensely decalcify - removing calcium - to reverse persistent stiffness and to seal in shine and suppleness. Expect hair that looks and feels stronger, healthier and shinier.

*Instrumental test on bleached hair after continued use of the full Première routine vs. non-bleached hair.

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