hard water

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hard wa·ter

water containing ions, such as Mg2+ and Ca2+, that form insoluble salts with fatty acids so that ordinary soap will not lather in it.

hard water

Etymology: AS, heard + waeter
water that contains certain cations, particularly calcium and magnesium, that precipitate with soap solutions. The term is generally applied to tap water, and the degree of hardness varies with the source and previous treatment.
Water with a high content of calcium and magnesium salts—e.g., carbonates and sulphates—which may interfere with certain lab tests

hard water

Water with a high content of calcium and magnesium salts–eg, carbonates and sulfates, which may interfere with certain lab tests. See Mineral water, Spring water; Cf Soft water.

hard wa·ter

(hahrd wawtĕr)
That containing ions, such as Mg2+ and Ca2+, which form insoluble salts with fatty acids so that ordinary soap will not lather in it.
References in periodicals archive ?
In the latter case, the continuous input of calcium through the supply of feeds to fish increases the hardness of water (HARGREAVES, 2006; POLEO et al.
Boiler water treatment formulation can be made from these dyes to remove hardness of water.
The Total Hardness of water is due to presence of cations, [Ca.
CORRELATIONS BETWEEN CALCIUM, MAGNESIUM AND HARDNESS OF WATER IN THE DRINKING WATERS OF DECATUR COUNTY GEORGIA AND THE INCIDENCE OF CARDIOVASCULAR AND CEREBROVASCULAR DISEASES, Abe A.
Severn Trent's price hike, announced last night, also includes pounds 15 million for tackling nitrates in Warwickshire's water, pounds 19 million improving the taste, odour and hardness of water in the county, pounds 4.
Hardness of water is caused by the presence of multivalent metallic cations and is largely due to calcium, Ca++, and magnesium, Mg++ ions.
Hardness of water may be due to high amounts of Ca, Mg and Fe.