What are the side effects of calcium in water?

October 27, 2025 •

4 min read

While drinking water with calcium is generally safe and provides essential minerals, high concentrations found in hard water can cause notable side effects. These effects range from nuisances in the home, like limescale buildup, to personal health issues, such as gastrointestinal discomfort and skin irritation.

Quick Summary

High levels of calcium in hard water can lead to digestive problems, skin irritation, and mineral buildup in plumbing and appliances. For most people, it's not a health risk, but can cause discomfort, especially for sensitive individuals.

Key Points

Gastrointestinal Distress: High calcium and magnesium levels in hard water can cause or exacerbate digestive issues like constipation, bloating, and stomach pain in some sensitive individuals.
Skin and Hair Problems: Hard water residue can dry out skin and strip its natural oils, worsening conditions like eczema and leaving hair dull and brittle.
Kidney Stones (Predisposed Individuals): While not a direct cause, excessive calcium intake from hard water can potentially contribute to kidney stone formation for those already at risk.
Appliance and Plumbing Damage: Limescale buildup from high calcium levels clogs pipes, damages water heaters and appliances, and reduces their efficiency and lifespan.
Sodium from Softeners: The most common solution, a water softener, replaces calcium with sodium, which can be a concern for those on low-sodium diets.
Metallic Taste: High mineral content can give drinking water a chalky or metallic taste, which may discourage adequate hydration.
Mineral Absorption Interference: Excess calcium can interact with other minerals like iron and zinc, potentially reducing their absorption in the intestines.

Understanding Hard Water and Calcium

Hard water contains high levels of dissolved minerals, primarily calcium and magnesium. Rainwater, which is naturally soft, becomes hard as it percolates through rock formations like limestone and gypsum, dissolving these minerals along the way. While these minerals contribute to our overall dietary intake and can be beneficial in moderation, excessive amounts in drinking water can lead to undesirable effects. The term "side effects" typically refers to the problems caused by this high mineral content, rather than a direct toxic reaction, as hard water is not inherently a health risk for the general population.

Digestive and Gastrointestinal Side Effects

One of the most commonly reported side effects of hard water with high calcium levels is an impact on the digestive system.

Constipation: Some individuals report experiencing constipation when regularly drinking mineral-heavy hard water. The high levels of calcium and magnesium can overwhelm the body's ability to process them, leading to digestive issues and inflammation.
Stomach Upset and Pain: The presence of excess minerals can lead to discomfort, including bloating, nausea, and general stomach pain, particularly for those with sensitive digestive systems or pre-existing conditions like IBS.
Altered Taste: The metallic or chalky taste of hard water can be off-putting for some, which might discourage adequate water intake. This can have knock-on effects for overall hydration and health.

Skin and Hair Issues

Beyond internal discomfort, the mineral content in hard water can have visible, external side effects on your skin and hair.

Dry, Irritated Skin: Hard water can strip the skin of its natural oils, leading to dryness, redness, and irritation. This can exacerbate conditions like eczema and psoriasis. The mineral residue can also clog pores and leave a film on the skin.
Dull, Brittle Hair: The calcium and magnesium in hard water can weaken hair fibers, leaving hair feeling dry, flat, and difficult to manage. The mineral deposits can build up on the scalp and hair, contributing to dandruff and dullness.

Appliance and Plumbing Problems

While not a direct health effect, the impact of hard water on household systems is a significant and costly side effect.

Limescale Buildup: The high mineral content causes limescale to accumulate on faucets, showerheads, and inside pipes, which reduces water flow and can lead to costly repairs.
Reduced Appliance Efficiency: Heating elements in appliances like water heaters and dishwashers are particularly prone to limescale buildup. This decreases their efficiency, shortens their lifespan, and increases energy consumption.
Poor Detergent Performance: The minerals react with soap and detergent, creating soap scum and reducing their effectiveness. This results in dingy clothes and spotty dishes.

Comparison of Water Hardness Effects


Feature	Soft Water	Hard Water	Potential Health Effects
Mineral Content	Low levels of calcium and magnesium	High levels of calcium and magnesium	Most people are unaffected, but high levels can lead to digestive issues in sensitive individuals.
Plumbing & Appliances	Reduced risk of mineral buildup and scale	Causes limescale buildup in pipes and on appliances.	Can release metals from pipes into water if too soft.
Skin & Hair	Less irritation, skin retains natural oils.	Can cause dry, irritated skin and dull, brittle hair due to mineral residue.	Worsens conditions like eczema and psoriasis for some people.
Taste	Often described as having a 'flatter' taste.	Can have a metallic or chalky taste.	An unpleasant taste may discourage proper hydration.
Potential Benefit	Does not provide a dietary source of calcium.	Can contribute to daily calcium and magnesium intake.	Potential protective effects against cardiovascular disease and cancer noted in some studies, but research is inconclusive.

Mitigating the Effects of Calcium in Water

There are several ways to manage the effects of calcium in water, particularly hard water.

Water Softeners: These systems use an ion exchange process to remove calcium and magnesium ions, replacing them with sodium. This is effective for protecting plumbing and appliances and can improve skin and hair health. However, the added sodium may be a concern for those on low-sodium diets.
Reverse Osmosis (RO) Systems: RO systems force water through a semipermeable membrane, effectively removing a high percentage of dissolved minerals, including calcium. They are highly effective for providing high-quality drinking water.
Regular Testing: It's important to test your water, especially if you have a private well, to understand your specific mineral levels. This helps determine the best course of action.

Conclusion

While calcium in water, often associated with hard water, is not a significant health risk for most individuals, it can present a range of side effects. These issues can affect a person's digestive health, skin, hair, and household plumbing. The potential health benefits from minerals in hard water are often outweighed by the practical nuisances it causes, especially for those with sensitivities. For those experiencing adverse effects, testing water hardness and considering a water treatment system, such as a softener or reverse osmosis, can provide effective solutions.

For more comprehensive information on the effects of hard water on your health, consult this publication: Potential Health Impacts of Hard Water: A Review of Literature

Frequently Asked Questions

For most people, drinking hard water is not dangerous and actually provides a minor supplement to your daily intake of essential minerals like calcium and magnesium. The World Health Organization has stated it has no known adverse health effects.

Hard water is not a direct cause of kidney stones, and most studies show no such link. However, some research suggests excessive calcium intake from water could be a contributing factor for individuals with a specific predisposition to kidney stone formation.

The minerals in hard water leave a residue that can clog pores and strip the skin's natural moisture, leading to dryness and irritation. For hair, the buildup can cause it to become dull, brittle, and difficult to manage.

Hard water contains high concentrations of dissolved minerals, mainly calcium and magnesium, picked up as it flows through rock. Soft water has a low concentration of these minerals.

The most effective methods are a water softener, which uses an ion exchange process, or a reverse osmosis (RO) system, which uses a semipermeable membrane to filter out minerals. Water softeners add a small amount of sodium to the water.

Yes, hard water can be a source of essential minerals and has been associated with some protective effects against cardiovascular disease in some studies. For those with low dietary calcium, hard water can provide a helpful supplement.

If you are on a low-sodium diet, the minimal amount of sodium added to softened water might be a concern. You can bypass the softener for your drinking water faucet to avoid this.