TABLE 4. WATER-QUALITY CHARACTERISTICS AND THEIR EFFECTS.
Constituent
or property Source or cause Effects
Silica (SiO) Dissolved from practically all Forms hard scale in pipes and boilers. Carried over in steam of rocks and soils, commonly less high pressure boilers to form deposits on blades of turbines. In03
than 30 ppm. High concen- hibits deterioration of zeolite-type water softeners. trations, as much as 100 ppm,
generally occur in highly alkaline waters.
Iron (Fe) Dissolved from practically all On exposure to air, iron in ground water oxides to reddish-brown so rocks and soils. May also be precipitate. More than about 0.3 ppm stains laundry and utensils derived from iron pipes, reddish-brown. Objectionable for food processing, textile processing, a pumps and other equipment. beverages, ice manufacture, brewing and other processes. U. S. More than 1 or 2 ppm of iron Public Health Service (1962) drinking-water standards state that o in surface waters generally iron should not exceed 0.3 ppm. Larger quantities cause unpleasant indicate acid wastes from taste and favor growth of iron bacteria. mine drainage or other sources.
0
Calcium (Ca) and Dissolved from practically all Causes most of the hardness and scale-forming properties of water; d Magnesium (Mg) soils and rocks, but especially soap consuming (see hardness). Waters low in calcium and magne- Z from limestone, dolomite, and sium desired in electroplating, tanning, dyeing, and in textile manu- 4 gypsum. Calcium and magne- facturing. sium are found in large quantities in some brines. Magnesium is present in large quantities in sea water.