hard water

American  

noun

1. water that contains magnesium, calcium, or iron salts and therefore forms a soap lather with difficulty.

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hard water Cultural  

1. Water in which dissolved minerals make it difficult to produce a lather with soap.

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Hard water is usually associated with well water in regions where the rocks contain a large proportion of iron-bearing minerals.

Example Sentences

Other plastics, including ones promoted as highly recyclable, such as clear polyethylene bottles, which hold some medications, or hard water bottles, are being recycled at just 16%.

From Los Angeles Times • Jan. 14, 2026

“It is abrasive enough to get through hard water and works great to polish surfaces. It has to have 0000 at the end,” she cautions.

From Seattle Times • Feb. 16, 2024

"Untreated hard water can leave mineral deposits on your clothes that dull their color and eat at their quality over time," explains Tim Dunphy, Water Expert at Leaf Home.

From Salon • Aug. 19, 2022

Some manufacturers recommend running a cleaning cycle periodically with no dishes but with citric acid, vinegar or a dishwasher cleaner to break up mineral deposits and remove films or stains from hard water.

From Washington Post • Aug. 1, 2022

She ask about hard water stains and I tell her cream of tartar.

From "The Help" by Kathryn Stockett