Softening is recommended when hardeness of water is more than?
ANSWER: (D) 150 mg/litreREF: Park 20th ed p. 636Indirect repeat from primary DNB CET December 2011Drinking water should be moderately hard. Softening of drinking water Is recommended when the hardness exceeds 3 mEq/L (150 mg/litre)ClassificationLevel of hardness (mEq/L)Soft water< 1 (< 50 mg/1)Moderately hard1-3 (50-150 mgd)Hard water3-6 (150-300 mg/1)Very hard water>6 (> 300 mg/1)
50 mg/litre
75 mg/litre
100 mg/litre
150 mg/litre
Water