Hard Water May Be Wrecking Your Hair—Here's How to Treat It

Not many people give much thought to the quality of the water their shower head disperses, but the type of water you are using to shampoo your hair can be more detrimental to its health than you think. Hard water, with higher-than-normal amounts of calcium, magnesium, and other minerals or heavy metals, can be the reason for limp locks and perpetual frizz. That's because as hard water accumulates on the hair and scalp, it can work against your best efforts to make every day a good hair day.

We enlisted the help of experts Dr. Joshua Zeichner and Shab Caspara to share everything you need to know about hard water hair damage, plus tips to prevent and treat future damage.

How Hard Water Affects Hair Health

According to Dr. Zeichner, water hardness is determined by the amount of calcium it contains. "Hard water is thought to be harsh on the skin, leading to skin barrier disruption and a loss of hydration resulting in skin inflammation throughout the body, including the scalp," he says. "Hard water can be particularly irritating and can lead to dryness, flaking, and itching of the skin."

Besides affecting the scalp, hard water can also wreak havoc on the hair, provoking dryness, brittleness, brassy hair color, and color fading. "Hard water can leave a hard-to-remove film on the hair and scalp that accumulates over time, leading to less than ideal hair conditions," says Caspara. "Minerals, like calcium, can change the hair color while iron can interfere with chemical treatments like highlighting, straightening or relaxing services." The buildup of minerals can also limit how much moisture the hair can absorb, leaving it looking and feeling dry, dull, frizzy, and hard to manage. 

Signs of Hard Water Hair Damage

Identifying hard water damage as the cause of your hair problems may not be the easiest to diagnose simply because not everyone understands the potential effects water can cause. However, there are a few signs to note, including a green or white coating on your shower head and sink faucets coupled with weak water pressure and dry, dull, frizzy, or limp hair.

Caspara says hard water may be the culprit if the hair never feels clean enough, causing you to over-cleanse it, which can dry out your hair or irritate the scalp. "Calcium in water mixes with shampoo to create a difficult-to-rinse-away soap scum that makes hair products ineffective," she explains. "When that happens, the conditioner cannot penetrate the hair and work efficiently."

When there's a buildup of minerals on the hair, it can lack shine and the ability to retain moisture, causing the hair's natural luster to fade. Hard water can also cause your color and highlights to fade fast and turn brassy. Split ends are also problematic since the hair's protective outer layer starts to slowly break down, causing the hair to split and break. And the scalp can feel tight or itchy due to the residue left behind. There's also a connection between excessive exposure to hard water and hair thinning. Caspara says hard water is harsh on the scalp and offsets the microbiome, causing inflammation and dryness. "When that happens, it can lead to hair thinning over time."

Hard Water Hair Treatments

When it comes to preventing the effects of hard water damage on the hair and scalp, the best place to start is with a device that can clarify the water and flush out the amount of hard minerals in it. Both water softeners and water filters are beneficial and have preventative effects, but Dr. Zeichner says each works differently. "Water softeners remove calcium compounds from the water whereas water filters remove other impurities," he shares. "You can purchase water-softening showerheads to soften the water you are showering with." Shower filters, such as Jolie The Filtered Shower Head and Cymbiotika Shower Filter, help to sift out other hair-damaging impurities and to help to some degree.

Even if you don't add a special water filter or softener to your shower head, there are other ways to combat the effects of hard water on the hair. Stick with gentle shampoos that don't strip the scalp and hair. Dr. Zeichner says that the general recommendation is to use ultra-hydrating hair products that help protect the outer layer of the hair from the damaging effects of calcium in the water.

There are also purifying shampoos and acidic rinses, like apple cider vinegar, with chelating ingredients. "Apple cider vinegar can help lower the hair's pH and break up any buildup," Caspara says. Pre-wash treatments, such as Colorproof Pre-Tox Spray ($31), are also important to implement into your hair care routine to help strip away hard water minerals, buildup, and residue. "To help safely and gently remove hard water buildup from hair, she recommends Virtue Refresh Purifying Shampoo ($32) for thicker hair types and Rahua Scalp Exfoliating Shampoo ($40) for more medium hair density types.

Purifying shampoos and rinses attract the minerals and lift them off the hair while smoothing the cuticle, so only use them weekly to prevent drying out the hair. And always follow up with a rich conditioner or hair mask to lock in moisture. No matter what you use on your hair to cleanse it, it's best to always shampoo and condition it with tepid or cool water rather than hot water. Caspara says hot water strips the lead and lime off pipes and deposits onto your scalp and hair.

Taking things a step beyond clarifying shampoos are hard water treatments, like Malibu C Hard Water Wellness Hair Remedy ($25) and L'Oréal Metal Detox Mask ($48), which remove minerals and metals and the residue they leave behind for stronger, shinier, healthier hair and better-looking color. Caspara says hard water hair treatments are essential, especially before any chemical service, such as highlighting, coloring, perming, straightening, or relaxing. "Any hard water buildup can interfere with chemical services and either exacerbate the damage done to the hair or result in an incorrect color outcome or have no effect at all."