What is Hard Water?
Hard water is defined by its high mineral content, primarily dissolved calcium and magnesium, which it acquires as it passes through natural rock formations like limestone and gypsum. While harmless to most people, the presence of these minerals can create various aesthetic and appliance-related issues within the home. Water hardness levels are categorized based on their concentration of calcium carbonate, expressed in milligrams per liter (mg/L).
Measuring water hardness
- Soft water: Below 75 mg/L
- Moderately hard water: 76 to 150 mg/L
- Hard water: 151 to 300 mg/L
- Very hard water: More than 300 mg/L
Potential Health Benefits of Drinking High-Calcium Water
Besides hydration, hard water can offer a nutritional boost. The minerals it contains, especially calcium and magnesium, can be absorbed by the body, supplementing dietary intake.
Contribution to daily mineral intake
For individuals with a borderline deficiency, the minerals in drinking water can provide an important contribution to their overall intake. The bioavailability of these minerals in water is also quite high.
Bone health
Research indicates a possible link between drinking high-calcium water and improved bone health. One study in Italy found that postmenopausal women who regularly drank calcium-rich water had significantly higher bone mass density. The World Health Organization also acknowledges hard water as a potential dietary source of essential minerals.
Cardiovascular health
Some large-scale epidemiological studies have observed an inverse relationship between water hardness and cardiovascular disease mortality. While not fully conclusive, these findings suggest a potential protective effect, possibly linked to the magnesium content.
Digestive health
Magnesium salts, often present in hard water, can have a laxative effect that may help combat constipation. Drinking hard water can therefore aid in maintaining regular bowel movements for some individuals.
Considerations and Potential Drawbacks
While generally safe, high-calcium water can present a few specific issues for certain people and households.
Skin and hair irritation
Hard water can leave behind mineral deposits on skin and hair, leading to dryness, irritation, and dull, brittle hair. People with pre-existing skin conditions like eczema may be particularly sensitive to these effects.
Gastrointestinal discomfort
Some sensitive individuals may experience mild digestive issues, such as bloating or discomfort, due to the high mineral content, particularly with very hard water.
Kidney stone myth
A common misconception is that hard water causes kidney stones. However, the formation of kidney stones is primarily influenced by other factors like diet and hydration levels, not water hardness alone. While excessive mineral intake is a factor, healthy kidneys typically excrete any excess calcium. Those with a predisposition or existing kidney conditions should consult a doctor.
Altered taste
Many people find the taste of very hard water unpleasant, describing it as chalky or mineral-heavy. This can impact a person's enjoyment of their drinking water.
High-Calcium Water vs. Softened Water
Homeowners seeking to mitigate the effects of hard water on their appliances, skin, and plumbing often install a water softener. This table compares the key differences.
| Feature | High-Calcium (Hard) Water | Softened Water (Ion Exchange) |
|---|---|---|
| Mineral Content | High in calcium and magnesium. | Low in calcium and magnesium, high in sodium. |
| Health Risks | Very low risk for healthy individuals. Potential for mild GI issues in sensitive people. | High sodium content can be a concern for individuals on low-sodium diets. |
| Potential Benefits | Contributes to daily mineral intake; possible cardiovascular/bone health benefits. | Preferred for cleaning and effectively lathering soap. |
| Household Effects | Causes limescale buildup in pipes and appliances, reducing efficiency and lifespan. | Eliminates mineral buildup, protecting appliances. |
| Taste | Can have a noticeable, sometimes chalky, mineral taste. | May have a slightly salty taste, though often imperceptible. |
Conclusion
Drinking water with a lot of calcium, or hard water, is generally safe and may even offer minor health benefits from the added minerals. The primary downsides are aesthetic and household-related, such as limescale buildup and effects on skin and hair, rather than serious health risks for the average person. Concerns about kidney stones are largely a myth for healthy individuals. If the aesthetic issues are a problem, a water softener is a viable option, though those on a low-sodium diet should be mindful of the increased sodium intake associated with some systems and consider a different water source for drinking. Ultimately, the choice to drink hard or softened water comes down to personal preference, taste, and tolerance for its household effects.
