If your home has hard water — water with a high mineral content — as many homes do, you are no doubt familiar with its downsides. Hello spotty glasses, soap that doesn’t lather, dry skin, dull hair, stains on porcelain and gunky-looking buildup around faucets and pipes.

Over the years, concerns have also been raised about hard water and its impact on a host of health issues including heart disease, fertility, Alzheimer’s disease, digestive issues and, most recently, eczema

Ronny Priefer, PhD, professor of medicinal chemistry at Western New England University in Springfield, MA, says hard water and health is a murky area of study. “There is plenty of conflicting evidence in literature,” he says. “Some scientists say there are health benefits; others say hard water harms health, and then there’s a group that claims no effect.” 

What makes water hard?

Water hardness is determined by mineral content. “Over sixty percent of the water that we consume is groundwater,” explains Priefer. “As water percolates through layers of rock, sand and soil, it gathers minerals. The higher the concentration of minerals, which include magnesium and calcium, the harder the water is.

One way hard water can benefit people, say experts, is by making up for the lack of calcium and magnesium they get from their diets. Not getting enough of these critical nutrients through foods is a problem for many Americans and can impact a person’s health. Inadequate intake of calcium, for instance, is linked with osteoporosis and high blood pressure. Magnesium deficiency, meanwhile, can trigger cardiac arrhythmias and Type 2 diabetes, among other health conditions.

In areas with naturally “soft” water supplies — such as the Colorado Mountains, where water comes from melting glacial ice and contains very little calcium or magnesium — people are often advised to add calcium and magnesium supplements to their diets, says Priefer. However, many people prefer soft water because it makes soap sudsier, gets clothes cleaner and is less corrosive. In areas with naturally hard water, homeowners sometimes add a filter to soften the water to remove magnesium and calcium.

Uncharted waters

But while drinking hard water might help increase our overall magnesium and calcium levels, to what extent does hard water improve or harm our health? In 2006, both the World Health Organization (WHO) and the National Institutes of Health (NIH) gathered a large contingent of experts from around the world to share scientific and medical findings regarding the safety of the world’s water supply, which included the impact of hard water on health. Report findings from both WHO and NIH stated that hard water has no known adverse health effects. Their report also said that magnesium in drinking water seems to have protective qualities for the heart, but most other positive associations need more study.

The NIH also addressed the epidemiological observations showing a relationship between drinking hard water and the risk for cardiovascular disease, growth retardation, and reproductive failure due to exposure to mineral content. They responded to these findings by saying that “many factors — including the acidity of the water — influence the reabsorption of calcium and magnesium in the body.” 

Similarly, the NIH addressed epidemiological studies linking areas where hard water is consumed with lowered rates of osteoporosis and reduced gastric cancer risk. Their response: “These disease patterns can be explained by social, climatological and environmental factors — rather than the hardness of the water.” 

They had the same response after reviewing studies linking magnesium with a mild to moderate protection against esophageal and ovarian cancer.

And what about the alleged link between hard water and Alzheimer’s? In this case aluminum — another mineral found in hard water — is the substance being called into question. According to the Alzheimer’s Association, studies have failed to confirm a direct link between Alzheimer’s and everyday exposure to aluminum, which is also used to make beverage cans and is an ingredient in antacids and baking soda. For now, the risk to brain health appears to be due to exposure to extremely high amounts of aluminum. 

“The NIH found in certain circumstances, such as a person who works in an occupation where there is massive exposure to aluminum — and then presents with symptoms similar to Alzheimer’s disease — the brain pathology looks similar to someone with Alzheimer’s disease,” says Priefer. “But there is no evidence that aluminum causes Alzheimer’s.” He adds: “The amount of aluminum — even in the hardest of water — is scant. Even over a lifetime, it would be nearly impossible to consume too much aluminum from drinking water. Large quantities would induce severe vomiting and other intestinal functions.”

Fertility concerns related to hard water were also unfounded, says Priefer, who says there’s no research to support claims that hard water reduces the quality or quantity of sperm.

“However, there is an interesting study from the UK which shows hard water exacerbates the symptoms of eczema in infants, and increases the frequency of the outbreaks,” adds Priefer. 

If you are curious about the mineral content of your water, Priefer suggests contacting your local government. They might be able to provide this info or put you in touch with the municipal treatment facility. Or, you can test your home’s water supply yourself. “There are do-it-yourself kits readily available at Home Depot and Lowes,” says Priefer.

Ann Matturro Gault is a freelance writer and editor whose work has appeared in national magazines and many websites. She lives with her four kids, dog, cat and spouse in New Jersey.