Dermatologists and data say yes
If you notice that your hairbrush has more hairs in it than normal and your ponytail is thinner, your water could be the culprit. Hard water contains calcium and magnesium ions which bond to the scalp and hair. This mineral layer interferes with the way shampoos clean, conditioners smooth, and moisture is retained in hair. This causes more knots, friction, breakage and the sensation (and reality) that hair is falling.
This is how it works. The hardness minerals in your shampoo react with other ingredients, reducing the effectiveness of lather and leaving behind a residue. This film can coat the cuticle of hair and clog up follicles. Detangling rough cuticles can lead to mechanical damage. These mineral interactions may also accelerate color fading if you color your hair. This can lead to frequent chemical treatments, and more damage.
While "clarifying" products may temporarily provide relief, frequent chelation will cause your hair to become even drier. It is best to find the cause.
The hardness ions are weakened by a tank-based, non-salt water conditioner. Shampoos and conditioners will work better if there are fewer minerals on your scalp and hair. You'll notice that your hair will feel smoother and less frizzy after a few washes. Reduced friction and residue will reduce the amount of breakage in your brush and drain.
Changes that are supportive can also help: use a gentle, non-sulfate shampoo as your water is being treated, detangle using a wide-toothed comb and avoid towel drying. The quality of the water is most important. Your routines will become simpler once you start showering with conditioned water. You will find that you require less product to achieve the same results. Colors will last longer and styling requires fewer heat treatments.
Is hard water the cause of every hair loss case? Not at all. Nutrition, hormones and general health can also have an impact. If you see signs like dullness, residue, difficulty in rinsing out, static, frizz and rapid color fade, then upgrading your water can be a simple, yet effective, way to improve your hair. Reassessment your routine after fixing the water.