If you’re plagued by dry, flaky skin, you probably figured you were just born that way. Or that it’s caused by “dry air.”
A new study shows the culprit may something you’ve never considered: Your water.
Hard water can cause eczema, the scaly, itchy skin condition that affects nearly 32 million Americans, according to new research from the University of Sheffield and King’s College London.1
The pH of your skin is naturally acidic. But hard water is high in the alkaline minerals calcium and magnesium. This combines with soap to raise your skin surface pH, scientists found.
That shift can damage your skin’s natural protective barrier. And it can make you more likely to develop eczema.2
Researchers recruited 80 subjects. Some had normal skin. Others had eczema. They washed the skin of each participant in water of varying hardness using commercial soap.3
They found that the calcium and magnesium in hard water reacts with a common soap ingredient called sodium lauryl sulfate (SLS). The minerals combine with SLS and leave a residue on the skin, the study found. This caused drying and irritation. It was particularly pronounced in people with a form of eczema called atopic dermatitis. But it even irritated the skin of people without eczema.4
Dr. Simon Danby led the study. He said: “Patients with eczema are much more sensitive to the effects of hard water than people with healthy skin.”
The study found that using a water softener helps. It reduces drying residues.
The research was published in the Journal of Investigative Dermatology.
If you or someone in your family has problems with eczema or other dry skin problems, check your water hardness.
If you’re on municipal water, you can get the numbers from your local water utility. If you are on well water, you’ll have to get your water tested yourself. You can get a home testing kit at some hardware stores and online. Tests can cost little as $5.
After you get you determine your water hardness number, compare it to this chart from the Water Quality Association.
If your number is in the hard to very hard range, getting a water softener might reduce dry skin problems your family may be suffering.
SLS-Free Soap: Help for Dry Skin
The study points to another solution. It showed there are two ingredients in the residues that raise skin pH. One is hard water. The other is SLS, the chemical in soap that helps make it foam or lather.
Switching to an SLS-free soap may also relieve dry skin. They can be difficult to find. But one brand is carried in many health food stores. It’s called Dr. Bronner’s. You can find other SLS-free soaps here.