What Does Calcium in Water Do to the Body? Benefits and Risks

November 29, 2025 •

3 min read

According to the World Health Organization, there is no convincing evidence that hard water causes adverse health effects in humans; in fact, the calcium in water can contribute to your daily mineral intake. This article explores what does calcium in water do to the body, highlighting its positive and negative impacts.

Quick Summary

Calcium in drinking water, particularly from hard water sources, can contribute essential minerals that support bone, nerve, and heart function. Potential downsides for certain individuals exist.

Key Points

Supports bone health: Calcium from hard water is a highly bioavailable source that contributes to stronger bones and teeth, similar to dairy.
Aids muscle and nerve function: This mineral is essential for proper muscle contraction, nerve impulse transmission, and maintaining a regular heart rhythm.
Generally safe for most: For the average, healthy individual, drinking hard water is not considered a health risk and can be a source of dietary minerals.
Potential kidney stone risk: In certain susceptible groups, particularly older women, high calcium water may be associated with an increased risk of kidney stones, though overall hydration is a more significant factor.
Consider your total intake: It is important to monitor overall calcium intake from all sources, including food, water, and supplements, to avoid excessive levels.
Bioavailability matters: Studies show calcium from water can be absorbed very effectively, making it a viable option for those who avoid dairy.

The Surprising Source of Essential Minerals

Calcium is crucial for the body, and while often associated with dairy, drinking water, especially hard water, is a source of this essential mineral. Hard water gets its mineral content, primarily calcium and magnesium, from passing through rock formations. For most healthy people, consuming hard water is not harmful and can aid in mineral nutrition. The effects can differ based on individual health and the specific water composition.

The Health Benefits of Calcium in Water

Water containing calcium, particularly mineral water, offers several health advantages:

Bone strength: Calcium is vital for strong bones and teeth. Studies indicate that calcium from mineral water is absorbed as effectively as calcium from milk, supporting bone health in all age groups.
Heart function: Calcium is involved in regulating heartbeat and blood pressure. Research continues to examine the potential link between water hardness and cardiovascular health.
Blood clotting: Calcium is a necessary component for the blood clotting process.
Muscle and nerve signals: Calcium ions are essential for muscle contractions and nerve transmissions. This includes the heart muscle's function.
Digestive aid: The minerals in hard water may offer mild antacid effects and help with constipation for some.

Bioavailability of Calcium from Water

The body effectively absorbs calcium from water. Studies show that calcium bioavailability from mineral waters is comparable to or potentially better than that from dairy. This is partly because calcium in water is in an ionic form, potentially easing absorption. This is particularly useful for individuals avoiding dairy. Spreading calcium intake throughout the day may improve absorption.

Potential Risks and Considerations of Calcium in Water

While generally beneficial, high calcium levels in hard water can present challenges for certain individuals. It's important to differentiate between calcium from water and excessive supplement intake.


Aspect	Hard Water (High Calcium)	Soft Water (Low Calcium)
Mineral Contribution	Provides valuable, bioavailable calcium and magnesium.	Lacks these beneficial minerals, which are often removed.
Health Impact	Generally beneficial, supports bone and heart health.	No direct health benefits related to mineral intake.
Kidney Stones	Potential increased risk for susceptible individuals, especially older women.	Lower risk related to water mineral content, but hydration is still key.
Digestive Issues	Can cause mild digestive discomfort in sensitive individuals.	Less likely to cause mineral-related digestive issues.
Sodium Content	Often associated with low sodium unless treated with a salt-based softener.	Typically higher in sodium, especially if treated with a salt-based water softener.
Plumbing/Appliances	Can cause limescale buildup, reducing appliance efficiency.	Can be corrosive to pipes, potentially leaching metals like lead.
Skin/Hair Effects	Can dry out skin and hair, leaving residue.	May feel 'soapy' but is gentler on skin and hair.

Kidney Stone Concerns

The most discussed risk of calcium in water is its potential link to kidney stones. Some studies suggest hard water with high calcium might increase kidney stone risk in females and individuals over 60. However, adequate hydration is a key preventive measure. Calcium oxalate stones are common, but sufficient dietary calcium can help bind oxalate in the gut.

Effects on the Digestive System

The high mineral content in hard water can occasionally lead to mild digestive issues like bloating or constipation in sensitive individuals. This is not a common problem for most people.

When to Be Cautious

Monitoring total daily calcium intake from all sources is important. Hypercalcemia, or excessive calcium, is more often due to supplement overuse or medical conditions than solely drinking water. Symptoms range from fatigue to more serious kidney and heart issues. Individuals with kidney issues, hypercalcemia, or those monitoring mineral intake should consult a healthcare professional. Salt-based water softeners replace calcium with sodium, which is relevant for those on low-sodium diets.

Conclusion

Calcium in water provides a bioavailable, calorie-free source of this crucial mineral, supporting bone health, muscle function, and cardiovascular health. While generally safe and beneficial, hard water's high mineral content might pose risks for specific groups, such as a potential increase in kidney stone risk for some individuals. A balanced overall intake, considering personal health, and staying hydrated are key. Consult a healthcare provider for personalized advice. For more detailed information on calcium absorption, refer to resources like the National Institutes of Health(https://www.ncbi.nlm.nih.gov/books/NBK56060/).

Frequently Asked Questions

While the link is complex and relies on individual risk factors, some studies suggest that hard water with a high calcium concentration may increase the risk of kidney stones in certain populations, such as females and those over 60. However, staying well-hydrated is key to prevention.

Yes, the calcium in water is a bioavailable source that can be absorbed by the body just as effectively as calcium from milk. It supports bone development in children and helps maintain bone mineral density throughout adulthood.

Multiple studies have shown that the bioavailability of calcium from mineral water is equivalent to or even better than that from dairy products. This makes water a valid supplementary source of dietary calcium.

Hard water contains high levels of dissolved minerals, primarily calcium and magnesium, from passing through rocks like limestone. Soft water has these minerals removed, often through a water softener that replaces them with sodium.

For most people, hard water does not cause digestive issues. However, individuals with sensitive stomachs might experience mild discomfort like bloating due to the high mineral content.

Water softeners can reduce scale buildup in appliances and improve the feel of skin and hair. However, they typically replace calcium with sodium, which might be a concern for those on low-sodium diets. For health benefits, it's possible to bypass the water softener for drinking water.

Washing with hard water can leave mineral deposits on your skin and hair. This can strip away moisture and lead to dryness, irritation, and clogged pores, potentially worsening conditions like eczema.