Calcium
An essential mineral and major contributor to water hardness, dissolved from limestone and other geological formations.
Calcium is one of the two primary minerals (along with magnesium) that determine water hardness. It dissolves into water as it passes through limestone, chalk, and dolomite formations.
Why it matters
There is no ADWG health guideline for calcium, as it is an essential dietary mineral. However:
- Scale formation: Calcium carbonate deposits (limescale) build up in kettles, hot water systems, and pipes
- Dietary contribution: Hard water can contribute meaningfully to daily calcium intake (up to 20% in areas with very hard water)
- Taste: High calcium levels contribute to a “chalky” or “mineral” taste
Relationship to hardness
Hardness is expressed as mg/L of calcium carbonate (CaCO3) equivalent. Both calcium and magnesium contribute, but calcium is typically the dominant component in Australian water.
Related Terms
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Disclaimer: Glossary definitions are provided for general educational purposes only and do not constitute medical advice or professional guidance. For specific health concerns about your drinking water, consult a qualified health professional. See our Terms of Use.