Hard water and tight skin: what the studies show
By Jeremy Fain, founder of Restelys. Updated 17 October 2026. 2 sources cited.
After a shower in a city with hard water, the skin feels tight. It is not just an impression: dermatology research has measured it.
So-called hard water is rich in calcium and magnesium. A team of British dermatologists showed that it increases the amount of washing agents left on the skin after a shower, and that this residue weakens the skin barrier, even more so in people with atopic skin.
It is one of the reasons the skin seems drier when travelling: the water changes, the soap stays. Hence two choices in our specifications: gentle cleansing bases without sulphates, and a body lotion designed for after the shower, with colloidal oatmeal and glycerin.
Our products do not treat any skin disease; they are designed to cleanse without aggression and to help the skin stay supple and comfortable, which is exactly the role of a cosmetic.
Sources
- Danby S.G. et al. “The effect of water hardness on surfactant deposition after washing and subsequent skin irritation in atopic dermatitis patients and healthy control subjects”. Journal of Investigative Dermatology, 2018.
- Perkin M.R. et al. “Association between domestic water hardness, chlorine, and atopic dermatitis risk in early life: a population-based cross-sectional study”. Journal of Allergy and Clinical Immunology, 2016.
The studies cited concern the ingredient or the skin, not our finished products.
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