Hardness is defined is the amount of dissolved calcium and magnesium in the water. These salts precipitate to form scales in boilers and heat exchange equipment and prevents lather formation when using soap.

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Hardness is undesirable in machine tool industry, poultry and in boilers as it interferes with the working of essential additives required for the process. Hard water is also unsuitable for domestic use in cleaning, washing and laundering. Some studies also indicate the role of hard water in heart diseases.

AquaPacific hardness kit uses titrimetric method to estimate Total hardness and is calculated as mg/l of CaCO3.