The hardness of Hard water (in mg/L) is
(PARK TB 25rd edition pg 787) Hardness is the soap destroying power of water. Level of hardness is expressed in terms of milliequivalents per litre where one milliequivalent is equal to 50mg calcium carbonate in one litre of water. The level of hardness of hard water is equal to 3-6mEq/L or 150-300 mg/L. CLASSIFICATION LEVEL OF HARDNESS (mEq./L) LEVEL OF HARDNESS (mg/L) soft water <1 <50 moderately hard 1-3 50-150 hard water 3-6 150-300 very hard >6 >300
<50
50-100
150-300
>300
Environment and health