AllChemicals — The Online Chemical Glossary | https://allchemicals.info/chemical/471-hard-water
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Quick Reference
Also Known As
Temporary hard water, permanent hard water, water hardness, scale-forming water
What is Hard Water?
Water containing dissolved calcium and magnesium ions, which prevent soap from lathering and cause scale deposits in pipes and kettles. Temporary hardness (caused by Ca(HCO₃)₂) can be removed by boiling; permanent hardness requires ion exchange or chemical treatment.
Properties & Characteristics
Hard water is water containing dissolved calcium (Ca²⁺) and magnesium (Mg²⁺) ions at concentrations sufficient to interfere with soap action (forming scum) and to form scale deposits. Temporary hardness is caused by Ca(HCO₃)₂ and Mg(HCO₃)₂ (removed by boiling); permanent hardness by CaSO₄ and MgSO₄ (requires chemical treatment or ion exchange). Total hardness is expressed in mg/L CaCO₃ equivalents.
Uses & Applications
Hard water treatment is important in: industrial boiler scale prevention, cooling tower operation, household water softening (ion exchange resins with Na⁺, or reverse osmosis), brewing (specific hardness profiles affect beer flavour), and swimming pool chemistry.
Safety Information
Hard water is not a direct health hazard (calcium and magnesium are essential nutrients). Scale in boilers can cause overpressure and explosions if heat transfer is impaired. Anti-scaling chemicals used in industrial systems (phosphonates, polyacrylates) may cause environmental concerns.
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
SynonymsTemporary hard water, permanent hard water, water hardness, scale-forming water
Frequently Asked Questions
Water containing dissolved calcium and magnesium ions, which prevent soap from lathering and cause scale deposits in pipes and kettles. Temporary hardness (caused by Ca(HCO₃)₂) can be removed by boiling; permanent hardness requires ion exchange or chemical treatment.
Hard water treatment is important in: industrial boiler scale prevention, cooling tower operation, household water softening (ion exchange resins with Na⁺, or reverse osmosis), brewing (specific hardness profiles affect beer flavour), and swimming pool chemistry.
Hard water is not a direct health hazard (calcium and magnesium are essential nutrients). Scale in boilers can cause overpressure and explosions if heat transfer is impaired. Anti-scaling chemicals used in industrial systems (phosphonates, polyacrylates) may cause environmental concerns.
Editorial standards: Chemical data is sourced from peer-reviewed literature,
CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA,
and IAEA. For educational purposes only — always consult official SDS documentation and qualified
professionals before handling chemicals.
