Hardness (water)
Description
The hardness of water is measured as the amount of total dissolved solids (TDS), such as sulfate calcium sulfate or carbonate magnesium carbonate. Hard water will leave a visible residue upon evaporation (limescale). It can also react with soaps to minimize bubble formation and to form an insoluble scum that interfers with cleaning. Hardness may be removed by distillation, by adding carbonate sodium carbonate and lime or by filtering the water. Filtration may be done with zeolites, an exchange resin ion exchange column or a osmosis reverse osmosis system.
Synonyms and Related Terms
Wasserhrte (Deut.); duret (Fr.); hard water; limescale; total dissolved solids (TDS)
Other Properties
TDS scale:
Soft water = 0-20 mg/l (calculated as calcium)
Moderately soft = 20-40 mg/l
Slightly hard= 40-60 mg/l
Moderately hard = 60-80 mg/l
Very hard = greater than 120 mg/l
Authority
- Hoechst Celanese Corporation, Hoechst Celanese Corporation, Dictionary of Fiber & Textile Technology (older version called Man-made Fiber and Textile Dictionary, 1965), Hoechst Celanese Corporation, Charlotte NC, 1990
- Richard C. Wolbers, Nanette T. Sterman, Chris Stavroudis, Richard C. Wolbers, Nanette T. Sterman, Chris Stavroudis, Notes for Workshop on New Methods in the Cleaning of Paintings, J.Paul Getty Trust, Los Angeles, 1990
- Wikipedia, the free encyclopedia, at http://www.wikipedia.com Comment: http://en.wikipedia.org/wiki/Hard_water (accessed Nov. 30, 2004)
- Random House, Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998