Softening Water

The Softening of Water

Water softening is a process that removes calcium, magnesium, and other ions from hard water.
Temporary hardness in water can be removed by boiling. This process precipitates out calcium carbonate which is the cause of temporary hardness.
Permanent hardness cannot be removed by boiling and is typically treated by using a process called ion exchange.
The ion exchange process often uses zeolites or ion-exchange resins which replace the calcium and magnesium ions in the water with sodium ions.

Chemical Softening of Water

Lime softening or Lime-Soda Ash softening is another method used to soften hard water. Lime is added to hard water to precipitate calcium and magnesium ions as hydroxides.
Chelating agents such as EDTA can bind to calcium and magnesium ions, preventing them from causing hardness.
Washing soda (sodium carbonate) can also be used to precipitate out calcium and magnesium, thus softening the water.

Mechanical Softening of Water

Water softening units, which use ion exchange resins, can replace calcium and magnesium ions with sodium or potassium ions.
Reverse Osmosis can also be used to soften water. This process uses pressure to force water through a membrane that retains the hardness ions and allows the soft water to pass through.

Remember, the techniques that you use to soften water depend on whether the hardness is temporary or permanent, and the specific ions present in the water.