Calcium and magnesium dissolved in water are the two most common minerals that make water hard. Water hardness is measured in three ways: grains per gallon, milligrams per liter (mg/L), or parts per million (ppm).
Many domestic water users are concerned about the hardness of their water. Hard water requires more soap and synthetic detergents for home laundry and washing, and contributes to scaling in domestic appliances like water geyser, washing machines and bath shower heads. Hardness is caused by compounds of calcium and magnesium, and by a variety of other metals. Water is an excellent solvent and readily dissolves minerals it comes in contact with. As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. Calcium and magnesium dissolved in water are the two most common minerals that make water “hard.”
Water Hardness Scale
|Grains Per Gallon||Milligrams Per Liter (mg/L)or Parts Per Million (ppm)||Classification|
|less than 1.0||less than 17.1||Soft|
|1.0 – 3.5||17.1 – 60||Slightly Hard|
|3.5 – 7.0||60 – 120||Moderately Hard|
|7.0 – 10.5||120 – 180||Hard|
|over 10.5||over 180||
In the past five decades or so evidence has been accumulating about this environmental factor, which appears to be influencing mortality, in particular, cardiovascular mortality. In addition, several health investigations have proved the relation between risk for cardiovascular disease, growth retardation, reproductive failure, and other health problems and hardness of drinking water. In addition, the acidity of the water influences the re absorption of calcium and magnesium in the renal tubule. Not only, calcium and magnesium, but other constituents also affect different health aspects.
A study conducted by the mines and geology department reveal’s that most of Bangalore’s ground water is contaminated with heavy metals. Nitrates, Iron and fluorides are in excess of permissible limits from a host of dyeing, metal fabrication, chemical industries and household detergent waste that are polluting the city’s lakes and water bodies.