Hard water
Water Treatment for Closed Heating and Cooling Systems (BG 50/2021), second edition, by Dr Pamela Simpson, published by BSRIA in 2021, defines hard water as: ‘Water with a total concentration of dissolved calcium and magnesium salts greater than 200 mg/l (as CaCO3).’
NB Approved document L, Conservation of Fuel and Power, Volume 2: Buildings other than dwellings, 2021 edition incorporating 2023 amendments, defines hard water as: ‘Water which has a high mineral content. For the purposes of this approved document, hard water is water that has a total water hardness of greater than 200ppm of CaCO3.’
--BSRIA
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