Total Hardness Testing

Total hardness is a measurement of the mineral content in a water sample that is irreversible by boiling. Total hardness is determined by the multivalent cations' concentrations present in water. These cations have a positive charge that is higher than 1+. Typically, cations have a charge of 2+. The most common cations present in hard water are Mg²⁺ and Ca²⁺.

Hardness is caused by calcium and magnesium ions in the water. The presence of bicarbonate ions affects the dose of chemicals required to precipitate the calcium and magnesium, and therefore hardness is classified in two ways:

• As calcium or magnesium hardness

• As carbonate or noncarbonate hardness.

Carbonate hardness is caused by calcium or magnesium ions associated with bicarbonate ions, and noncarbonate hardness is caused by calcium or magnesium ions associated with chloride, sulfate, or other ions.

Hardness also relates to the scale that precipitates in kettles and utensils when water is boiled. The form of hardness produced on heating is the temporary, or carbonate, hardness consisting of calcium and magnesium bicarbonates. Permanent, or non-carbonate, hardness (which is not precipitated by heating) is due to other minerals or salts of calcium and magnesium, such as sulphates, that may be present in the water.

Consumers living in hard water areas complained about the scale of deposition on kitchen utensils and increased soap usage, with associated scum formation. Conversely, waters containing less than 30–50 mg/l total hardness tend to be corrosive and may need additional treatment to reduce the risk of plumbo- and cuprosolvency.

Hard water is not that harmful to human health. However, water with a high level of hardness could cause serious problems in industrial settings wherein water hardness is typically monitored to prevent costly failures in components like cooling towers, boilers and other equipment that contains or processes water.

Various measures and kits can be used to measure the magnesium and calcium present in the hard water. These two essential minerals are the main cause of water hardness.

Hardness can be quantified using instrumental analysis. The total water hardness is the sum of the molar concentrations of Ca2+ and Mg2+, in mol/L or mmol/L units. Although water hardness usually measures only the total concentrations of calcium and magnesium (the two most prevalent divalent metal ions), iron, aluminium, and manganese can also be present at elevated levels in some locations. The presence of iron characteristically confers a brownish (rust-like) color to the calcification, instead of white (the color of most of the other compounds).Hardness is most commonly measured by titration with an EDTA solution, test strips, colorimeter, and spectrophotometer.

Alfa Chemistry is professional in water impurity analysis and we can provide accurate and reliable tests results within the time constraint. We have conducted well water analysis, drinking water quality analysis, watersheds and rivers analysis and wastewater, stormwater, runoff analysis.Please feel free to contact us if you have any concern or would like us to perform any water total hardness testing. Check our instruments list to see our capabilities.