The Buildup Breakdown: How Minerals and Metals Impact Hair

When you think about hair buildup, your mind might go straight to leftover conditioner or dry shampoo. But buildup isn’t just product residue. Several additional factors can impact hair, originating from the body, like natural oils, as well as the environment, like air pollution, and even minerals or metals from shower water.^1,2 

Shower water is an environmental exposure our hair has to deal with regularly. Hard water has a high concentration of dissolved minerals—primarily calcium and magnesium. It forms when groundwater passes through limestone or chalk, picking up minerals and sometimes even trace metals, like iron or copper. Hard water is a problem in over 85% of the United States, which means most of us are exposed daily.³

You can spot hard water in your home if you notice a slimy film on your hands after washing, cloudy glassware, or a white, crusty buildup on your showerhead. If you’re unsure, the EWG Tapwater database is a good resource to check by zip code. If you want precise details about your home specifically, some cities and companies provide water testing.

The outer layer of your hair (called the cuticle) is made of a protein called keratin that’s held together by chemical bonds. When your hair gets wet, those bonds loosen slightly, which lifts the cuticle, so water (along with whatever’s in it) can seep in. That’s when minerals and metals in the water can attach themselves to your hair fibers, leading to breakage and more fragile hair over time.^4,5

If your hair is colored, bleached, or chemically treated, it’s even more vulnerable because these chemical processes make it easier for minerals and metals to enter and bind to hair strands.⁶

Over time, mineral and metal buildup doesn’t just coat your hair; it can change its structure.

Studies show that hair exposed to hard water tends to have a rougher surface, reduced thickness, and lower tensile strength, meaning it can break more easily.^4,6 This causes hair that feels dull, dry, or tangly—no matter what conditioner you use.

And it’s not just calcium and magnesium that can damage hair. Heavy metals like iron, copper, lead, or cadmium (a metal found in both water and air pollution) can cause similar problems.^1,2 These metals can dull color-treated hair and make strands feel more coarse.⁷

Air pollution, like from car exhaust or industrial facilities, adds another layer of complexity. Tiny airborne particles can stick to sebum (the natural oil on your scalp and hair), worsening buildup and further dulling your shine.⁸

It’s important to remember: while chemically treated hair is more vulnerable, undyed hair isn’t immune.⁹ Hard water and environmental exposure can eventually affect any type of hair.

There’s no need to worry if you find out you have hard water in your home. Thankfully, there are ways to help protect your hair from the damage caused by hard water and help restore its health.

1. Water treatments

If your area has hard water, consider these home water treatments:

2. Cleansing treatments.

Even with the best water treatments, it’s important to use products that will cleanse your scalp—from water, air pollution, and other buildup—while supporting the scalp’s microbiome. 

Mineral and metal exposure through hard water is an incredibly common issue affecting not just the look of your hair, but also its health—in some cases, leaving it rough, dull, and prone to breakage. If you’ve noticed any of these changes in your hair, mineral or metal buildup could be part of the reason. 

There are ways to lessen your exposure to minerals and metals from hard water. By combining water treatments or filtration with a consistent hair care routine that includes cleansing shampoos or ACV rinses, you can help minimize metal buildup for smoother, stronger, healthier hair.