Hard water is bad for your hair – so can hard water shampoos fix your locks?

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Hard water shampoos and treatments are sprouting like mushrooms, with search increases for ‘clarifying’ and ‘detox’ shampoos in the triple digits. But are we looking at just another expensive fad to complicate your routine?

Well, when you find out what the stuff in hard water actually does to hair, especially if it’s processed or naturally dry, you may decide a hard water shampoo is are an investment worth making. Here’s how to recognise if there’s something unpleasant lurking on your water, and how to counteract it with products that work.

What is hard water?

It’s water that’s high in natural minerals and/or heavy metals such as calcium, zinc, magnesium, iron, lead and copper; it’s estimated 60% of Europe is a hard water area, and that includes greater London. Chlorine tends to be in there as well, as a disinfectant. It’s perfectly safe to drink, but it’s not so gentle on your hair and skin, which can be left dry and vulnerable.

What does hard water do to hair?

These substances can kill healthy bacteria on the skin, messing up its natural defences against moisture loss and irritants. They can dry hair out in the same way, and once absorbed in the hair, heavy metals can form free radicals that attack healthy protein fibres and leave your hair damaged. Also, says Kelli Durant, head of education at Living Proof, “minerals will build up on the hair shaft, hardening it. This increases friction, turning hair weak and brittle.”

Some tell-tale signs of hard water damage:

  • Hair becomes dry, brittle and lacklustre
  • A lot of crispy-feeling build-up in your hair will leave it feeling coarse
  • A dry and flaky scalp.
  • Fast colour fade
  • Colour distortion: both natural and salon colour can go dull or brassy. “Iron can tint light-coloured hair orange and dark hair reddish,” says Karlee Ozener, founder of Hello Klean. “Oxidised copper (chlorine + copper) can discolour light hair, producing a green tint.”

Beyond your hair, Ozener says, you might notice that soap doesn’t lather very well, clothes feel rough to the touch, you see yellow, green and rusty stains on the enamel of your bath and your showerhead, and symptoms of eczema and psoriasis on your skin and scalp can worsen.

What hair types need a hard water shampoo?

The moisture and lipid-stripping, hair fibre and scalp-damaging effects of hard water mean that a hard water shampoo or treatment is particularly helpful if your hair is already vulnerable from lots of processing (bleaching, perming, relaxing, constant heat styling), or if your hair and scalp are naturally dry or sensitive (this includes naturally grey hair). Fine hair needs extra help to fight its propensity for mineral build-up, and Afro hair, which needs plenty of natural oils to maintain its good looks, can really benefit from these shampoos as well.

How do you get rid of hard water build-up in hair?

When it comes to hard water shampoos, the trick is to deep-cleanse without any harshness or aggression, as stripping ingredients would only exacerbate the damage done by the water contaminants. “Unlike most once-a-week ‘detox’ shampoos, which primarily target styling products that leave hair limp and greasy, hard water shampoos are formulated not to dry the hair and scalp, and won’t leech colour from the hair,” says Ozener. “They combine very mild cleansing agents with special ingredients that bind to metals and minerals and lift them from the hair shaft, so they purify without causing any upset.”

Oils and other conditioners often feature in hard water shampoos and pre-shampoo treatments as well, to help fortify brittle hair and prevent against future build-up. Although Durant cautions against any products “too loaded with heavy conditioning agents, which can weigh hair down.”

What should you look for in a good hard water shampoo or treatment?

Here are the goodies to look for in products that fights hard water (which are sometimes called ‘clarifying’, ‘balancing’ or, indeed, ‘detox’ shampoos or treatments).

  • Mild non-SLS sulphate surfactants (cleansing agents) such as decyl glucoside and coco-betaine
  • Chelating (metal- and mineral binding) agents. Examples are disodium EDTA , citric acid, vitamin C and bamboo charcoal and sodium gluconate.
  • Vinegar such as apple cider vinegar (ACV), which gently dissolves minerals and metals, rebalances and soothes the scalp microbiome, and adds shine.
  • Acids such as lactic acid to hydrate and smooth and seal the hair shaft, preventing build-up.
  • Oils and conditioners to condition and fortify damaged hair. Not-too heavy ones are hydrolysed oat proteins, amino acids, panthenol and polyquaternium-10.

Does a hard water filter work?

The most effective way to combat hard water deposits in hair is a combination of the right shampoo and installing a showerhead filter or water softener,” says Durant.

“What happens is that the heavy metals and chlorine in bond with ingredients inside the filter, creating new, harmless elements,” says Ozener. Chlorine, for instance, will shift into harmless chloride. While a filter will help remove many water contaminants before they reach your body, Ozener adds that “it’s still worth using a hard water shampoo as well to further counteract the effects.” Those who’ve tried a hard water filter are often converts, reporting noticeable improvements in their hair and skin.

‘Hard water’ hair conditioners will help off-set some of the damage sustained, but don’t actually do anything to rid hair of contaminants.

The best hard water shampoos and treatments

Best for fine hair: Malibu C Hard Water Wellness Shampoo, £16.50

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Although sulphate-free, this Solero-scented shampoo still uses pretty intense clarifying and chelating agents, so use a moisturising hair mask afterwards. It leaves hair feeling very light and helps repair it with conditioning proteins.

Best for limp, brittle hair: Living Proof Clarifying Detox Shampoo, £31

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This may be called a ‘detox’ shampoo, but “we use gentle cleansers and polymers that act like a magnet, attracting product buildup and so gently removing it from hair,” says Durant. Chelating agents and charcoal are in here as well for effective once-weekly removal of heavy metals, pollutants and grime, all the while brightening, not dulling, your colour.

Best for bleached and over-processed hair: Kerastase Premiere Decalcifying Repairing Pre-Shampoo Treatment, £55.465

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With citric acid to filter out dulling calcium deposits and the amino acid glycine to repair brittle strands, this lotion leaves hair softer, brighter and stronger when left on for five minutes before shampooing.

Best hard water filter: Hello Klean Purifying Shower Head, £59

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Has a two-step filtration process to get rid of most contaminants in hard water, and reduces water use by 25% but doubles its pressure. Comes with one cartridge (refills are £40 each) that lasts about four months.

Best value for dry, delicate hair and scalp: Aveeno Haircare Clarify & Shine+ Apple Cider Vinegar Shampoo, £7.99

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Based on ACV and mild chelating agents and containing conditioners and soothing colloidal oatmeal, this gently dissolves build-up while softening hair, adding shine and calming upset scalps.

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A favourite for reviving dulled, crispy-feeling hair whose colour has been distorted by the scourge of mineral and metal deposits, spritzing this on pre-shampoo and leaving it for three minutes, three times a week, will transform both colour and texture, even that of coarse hair.

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A fresh-smelling shampoo with gentle surfactants and chelating agents, teamed with conditioners to brighten dehydrated hair that’s beset by discolouration and colour fade. Great for lighting up your highlights and making grey hair look vibrant.

Best for dull, rough hair: R+Co Tea Cup Detox Rinse, £30

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A very gentle, fermented kombucha-powered pre-shampoo conditioning rinse with a handy nozzle, it purifies your scalp but also softens and conditions dry ends while brightening colour and taking the brassiness out of highlights.

Best for Afro or coarse hair: Moroccanoil Clarifying Shampoo, £20.85

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Gentle cleansers, chelating agents and a host of conditioners (panthenol, keratin, argan and avocado oils) will deal with the roughness and dulling that hard water causes while hydrating glycerine and lipids, so needed when your hair is curly, coarse or very dry, will help restore it.