Hard Water Is Damaging Your Hair—Here's How to Stop It

Hard water sounds like an oxymoron (or, actually, maybe a great name for a record label). All water is… liquid, so how could it be hard? 

When we talk about hard or soft water, we’re not actually talking about its density or feel. The scale of hard to soft refers to the concentration of minerals in the water. The more calcium and magnesium (or iron, copper, lime, sodium, and so on) the water has, the “harder” it is. You can’t actually see these minerals, but it’s pretty likely that you have hard water at home. In fact, if you check out a hard water map, you’ll see that about 85% of the U.S. does. 

First and foremost, don’t panic. This doesn’t affect the safety of your water. Drinking hard water can actually help you hit your daily recommended intake of essential minerals. 

But perhaps a more important question: What is this mineral-rich water doing to your hair? Can hard water damage your hair? Is there some way to prevent the damage? We asked three experts for their help—keep reading to learn all about hard water damage to hair and how you can counteract it.

What Does Hard Water Do to Hair?

Think about how dry and crunchy your hair feels when you let it air-dry after swimming in the ocean—that’s just an exaggerated example of what hard water can do to your hair. That crispy feeling is the mineral residue clinging to your hair as the water evaporates (in this case, sodium—albeit a much higher concentration than in your average tap water). 

Minerals in tap water act similarly.  “While your hair is wet, the minerals from hard water can penetrate your strands and crystallize as your hair dries,” says hairstylist Devin Toth. “The crystallization creates a cast that prevents moisture from getting in or out of your hair.” That means drier, duller hair more prone to tangles and breakage.  

No one with hard water is truly impervious to damage, but some hair types might feel it a bit more than others. “Hair textures that are highly porous are more susceptible to minerals penetrating deeper into the hair structure, making it more susceptible to hard water,” says trichologist Bridgette Hill. “Color treated and chemically treated hair fall into this category.” Toth adds that curly hair types will also feel the effects of hard water a bit more, since their hair is already prone to dryness and frizz.

Minerals build up over time and can cause a butterfly effect of other issues. It can cause colored hair to fade or change (that’s why truly color-safe products are sulfate-free). You may notice that your scalp is dry, flaky, or even greasier than normal. It can weigh down your hair and make styles look flat. It can even irritate skin prone to eczema.

How to Know If You Have Hard Water

If you're trying to figure out whether you have hard water, this is where you’ll need to do a little detective work, but the good news is there’s several ways to learn what kind of water you have. 

When hard water evaporates, it leaves the minerals behind. If you’ve ever seen water droplet residue on a glass after you take it out of the dishwasher, you’re looking at a mineral deposit from your water. The same goes for your faucets and appliances, “Look for filmy, crystallized hard water deposits on your shower head,” says Toth. If you’re constantly battling a powdery white or greenish coating on and around your faucets—that’s a good sign that you have hard water.

Because the minerals in hard water tend to build up and coat pipes and faucets, you’ll also likely have low water pressure in the shower and in your sinks. If you’re not getting enough power when you crank a sink to 10, it could be a side effect of hard water.  

Your hair could also be a telltale sign. “If your shampoo takes an extra long time to lather or properly distribute, then you may have hard water,” says Toth. “Or if your high-quality conditioner doesn't seem to work and after using it your hair feels dry and tangly—then there's a good chance your hair is being affected by hard water.”

In the end, the most surefire way to detect hard water is to purchase a small hard water testing kit. Trichologist David Adams recommends the Life2O Water Hardness Test Strips ($10 for 100), but there are tons of equally effective options. They’re generally affordable and easy to use—just dip a test strip in a cup of water, wait a minute, and then compare your results to a color chart.

How to Prevent Hard Water Damage

So you have hard water. Now what? Well, you can’t help where your water comes from. If you live in an area that sources water from subterranean aquifers, springs, or rivers, it will just naturally have more minerals (Check out that map again—states in the Midwest, where the Mississippi River is a major water source, have the highest concentration of hard water in the country). But there are a few steps to not only lessen hard water damage, but repair it.