hard water

(redirected from Water hardness)
Also found in: Dictionary, Thesaurus, Encyclopedia.
Related to Water hardness: water softener

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.
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 ?
Lack of association between water hardness and coronary heart disease mortality in Japan.
The process principle is based on a calcium-magnesium-selective electrode, which constantly determines the difference in water hardness between hard and soft water and evaluates to a predetermined threshold value.
Effects of water hardness, alkalinity, and dissolved organic carbon on the toxicity of copper to the lateral line of developing fish.
This means that the process could potentially be viable across a wide array of regions, regardless of water hardness.
This research determined and assessed the quality of tap water sources in Manila City, Philippines in terms of water hardness measured in ppm CaC[O.sub.3].
Water hardness was related to the occurrence of urolithiasis in Turkey where the mean hardness of water sampled was 285 ppm (285 mg [l.sup.-1]) and was greater than the acceptable limits for water hardness (SAHINDURAN et al., 2007).
Water hardness, determined by the amount of dissolved calcium and magnesium in the water, varies by geography and mineral content of the water supply.
Studies of children in the United Kingdom, Spain, and Japan show the prevalence of AD is significantly higher in the highest water hardness categories than that in the lowest.
Keywords: Bi-functional reactive dyes, Water hardness, Ca, Mg, Fe
Four categories of water hardness can be identified based on the CaC[O.sub.3] hardness [20]: CaC[O.sub.3] hardness below 60 mg/L: soft; 60-120 mg/L: moderately hard; 120-180 mg/L: hard; and more than 180 mg/ L: very hard water.