hard water

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Related to Water hardness: water softener

hard water

[′härd ¦wȯd·ər]
(chemistry)
Water that contains certain salts, such as those of calcium or magnesium, which form insoluble deposits in boilers and form precipitates with soap.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

hard water

Water containing solutions of mineral salts (sulfates of calcium and magnesium, carbonates, and bicarbonates). Also see water softener.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
Likely, the differences in the values of these N[H.sub.3] safe levels are related to the protective effect of higher water hardness levels against N[H.sub.3] toxicity (TOMASSO, 1994).
Finally, data on drinking water hardness have also been completed and updated as a result of efforts to build a comprehensive environmental database inside the RIF.
The residual hardness is determined randomly by means of color change, the residual water hardness value determined is compared with the specified soft water threshold value and the alarm is triggered when the threshold value is exceeded.
Biomass = Dry weight of planktonic biomass (mg L-1)###R2 = Co-efficient of determination###Temp = Temperature (AdegC)###Hard = Total water hardness (mg L-1)
Water hardness refers to the amount of dissolved minerals in the water.
Auto maintenance: Receive alerts about when to clean the filter or to start the drum cleaning cycle, based also on your water hardness.
For example, water hardness varies throughout the U.S., and this can affect flavour.
Water hardness is the measure of the number of polyvalent cations ([Ca.sup.2+], [Mg.sup.2+], and [Fe.sup.3+]) present in a water sample [1] and is usually expressed in terms of parts per million calcium carbonate (ppm CaC[O.sub.3]).
Analysis of water quality parameters (temperature, pH, dissolved oxygen, ammonia, nitrite, water transparency, total alkalinity, and water hardness) was carried out every 30 days following a standard protocol (APHA, 1995).
Projects during the fall term include quantitative analyses of water hardness, alkalinity and dissolved oxygen to assess the health of aquatic resources; the concentration of copper, lead and zinc in digested plant samples collected from two areas of concern from point source and non-point source pollution; and concentration and form of macronutrients in soil to include nitrogen, phosphate and potassium as well as salinity, ion exchange capacity, and pH to determine soil productivity.