Hardness of water is expressed as milli-equivalent per litre (mEq/L), one unit of which is equivalent to which one of the following -
Hardness of water us expressed in milliequivalents/L. One mEq/L is equal to 50mg of CaCO3(50 ppm) in one litre. Park's Textbook of Preventive and Social Medicine, 25th edition, Page No. 786
20 mg CaCO3 (20 ppm)
30 mg CaCO3 (30 ppm)
40 mg CaCO3 (40 ppm)
50 mg CaCO3 (50 ppm)
Environment and health