The degree of hardness in a water source is determined by its level of positively charged ions such as calcium and magnesium. These ions usually find their way into a water source by slowly dissolving and leeching over time from minerals such as calcite and gypsum that are found in aquafers, bores, river systems, and other natural water collection points. Water hardness is broken down into two types, where each type is determined by the specific mineral content and amount found within the location of the water collection point.
The first type of water hardness is temporary hardness. Temporary hardness is predominantly caused by the presence of calcium bicarbonate and magnesium bicarbonate. Once dissolved, these minerals will release calcium and magnesium cations as well as bicarbonate anions. Whilst these minerals make the water technically ‘hard’, this type of hardness can be significantly reduced by boiling. The boiling action will cause a precipitation of solid calcium carbonate and or magnesium carbonate from the water, which will make it softer than it was before boiling. This process is the reason why we see scale build-up in separate chunks at the base of a coffee machine boiler, rather than enveloping the entire boiler casing.
The second type of water hardness is permanent hardness. This hardness type refers to the mineral content in water that is not possible to be removed through the action of boiling. This type of hardness is typically caused by calcium and/or magnesium sulphates, which unlike the carbonate variants do not precipitate out at increased temperatures and are less soluble when hot than cold. When permanent hardness occurs, the scale seen within coffee machine boilers caused by the contaminant being pulled from the water directly onto heat transfer surfaces tends to be heavy and evenly spread over the surface. The deposits will be much harder and more dense when compared with the carbonate variant as their smaller crystal-like shape and size allows them to form together more tightly.
For more information or assistance with water hardness or the removal of scale build-up, send our team an email at [email protected] or give them a call on 1300 724 249.
