Most hair routines get rebuilt from the product shelf backward. Something feels off, so you buy a new shampoo, then a new mask, then a new leave-in. In a hard-water home that order is backward. The water touches your hair before any of it does, so check the water first.
A hardness strip dipped in your shower water gives you a band in a few seconds. Your utility's annual water quality report gives you a number for the whole system. Either is enough to place you in one of four classes: soft (0 to 60 mg/L), moderately hard (61 to 120), hard (121 to 180) or very hard (above 180).1 See testing your water at home and what ppm means.
Soft water does not end the investigation, it moves it. If you test soft, skip to check 5.
Your shower has been running the experiment for months. The stains are the result.
| What you see | Likely metal | What it can do to hair |
|---|---|---|
| White, chalky crust on the showerhead, spots on glass | Calcium and magnesium | Dull, coated, rough film |
| Rusty orange or reddish stains | Iron | Orange cast, especially on light hair |
| Blue-green stains around drains or fixtures | Copper | Green cast, trouble with lightening |
Iron and copper staining are the reasons the EPA sets cosmetic, non-health limits for those metals in drinking water.2 A strip that reads hardness will not see either one, so trust the stains. More in well water and iron and copper and hair color.
Wet hair hides build-up. Wait until it is fully dry after a normal wash, then check:
Lab work on hair swatches found that already-processed hair, colored, lightened or heat-damaged, takes up more calcium and magnesium than unprocessed hair.3 So if your ends feel worse than your roots, that fits.
Hair rarely goes from fine to bad overnight for no reason. Write down anything new in the last two to three months: a move, a new apartment building, a dorm, a long trip, a gym shower, pool season, a lightening service. A change that lines up with the timing is the strongest single clue on this list. See why your hair changed when you moved.
Three problems feel almost identical to mineral build-up, and each one has the opposite fix:
| Checks pointing at water | What to do |
|---|---|
| 0 to 1 | Your water is probably not the story. Look at products, heat and protein first. |
| 2 | Possible. Try one clarifying wash. If the coated feel comes back within a week, move to the next row. |
| 3 or more | Treat the build-up first, with a wash designed to bind minerals, then match how often to your band. See how often to chelate. |
One small habit that does help: finish with an acidic conditioner. Lower pH is associated with a smoother, lower-friction hair surface, which is part of why a good conditioner feels the way it does.4
If your scalp is itchy, flaking, burning or sore, if you are losing hair from the root in clumps, or if you see patches or a widening part, see a dermatologist. This post covers cosmetic build-up and the feel and look of hair, not hair growth or any medical condition.