Hard water is tap water that's high in minerals such as calcium and magnesium. Hard water isn't harmful, except the minerals prevent your soap from sudsing. Some people think that hard water is more likely to cause a rash than soft water.
Take a recent patient of mine: He moved his family to San Diego from the East Coast (good move this winter, no?) After they moved here, they noticed their skin became dry and itchy. He blamed San Diego's notoriously hard water and installed a water softener in the main water line. It was costly, but did it improve their skin?
A recent study from the U.K. looked at this question: Does hard water worsen eczema? The answer was no, it doesn't. Water hardness did not seem to have any impact on eczema, the most common skin rash.
What's more important than the hardness of the water is the type of soap you use. True soap tends to strip the skin of its natural oils, leaving it exposed and irritated. Non-soap cleansers, of which Dove is the prototype, leave more oils on your skin, keeping it hydrated and protected.
My patient and his family didn't get any better after installing a water softener (although he said they could drink our tap water without gagging now.) I advised him to change to a moisturizing soap and to apply moisturizer daily.
San Diego is drier than most of the country, and the low humidity can be a shock to skin accustomed to humid air. Many people who move here find they have to moisturize more often than they did back home. When they complain, I suggest they could alternatively move back to the East Coast this winter--no takers so far.
This post by Jeffrey Benabio, MD, appeared at Get Better Health, a network of popular health bloggers brought together by Val Jones, MD. Better Health's mission is to support and promote health care professional bloggers, provide insightful and trustworthy health commentary, and help to inform health policy makers about the provider point of view on health care reform, science, research and patient care.