There are two main types of hardness in water: temporary hardness and permanent hardness.
Temporary hardness:
- Temporary hardness is caused by the presence of bicarbonate ions (HCO3-) in water, which can dissolve into calcium (Ca2+) and magnesium (Mg2+) ions and carbonate (CO32-) ions.
- This type of hardness can be removed through boiling, as the bicarbonates will precipitate out of solution and form solid particles that can be filtered out.
Permanent hardness:
- Permanent hardness, on the other hand, is caused by the presence of dissolved calcium and magnesium ions in water that cannot be removed through boiling.
- Permanent hardness is usually due to the presence of minerals such as calcium sulfate (CaSO4), magnesium sulfate (MgSO4), and calcium chloride (CaCl2).
- Permanent hardness can only be removed through physical or chemical treatment methods, such as ion exchange or reverse osmosis.