<prompt> 1 meq L of hardness of water is equivalent to presence of:25 mg calcium bicarbonate in 1 litre of water50 mg calcium bicarbonate in 1 litre of water100 mg calcium bicarbonate in 1 litre of water150 mg calcium bicarbonate in 1 litre of water  <response>: Hardness of water is expressed in meqL. 1 meqL of hardness producing ion is equal to 5o mg of calcium bicarbonate in 1 litre of water. Ref: Park 21st edition page: 671. 