Hard & Soft Water – Ways to Softening of Hard Water

Soft and Hard Water

You have actually most likely heard the terms “hard water” and “soft water” You may wonder what determines the hardness or softness of the water and whether one kind of water is healthier or much safer to drink than the other.

Although water is generally crystal clear, it consists of minerals and chemicals. The concentration of specific minerals is what develops the “hardness” of water.

First of all, for your understanding here are discussed proper definitions of soft and hard water. And then the ways to get rid of hard water.

Soft water

The water which is immaculate by chemicals is called soft water. Soft water produces a good lather with soap.

Hard water

The rainwater while coming down absorbs CO2 from the atmosphere. The water blended with CO2, when passes through the beds of the soil, transforms insoluble carbonates of calcium and magnesium into soluble bicarbonates. It might also liquify chlorides and sulphates of calcium and magnesium. These salts make the water hard.

Hard water does not produce lather with soap.


Therefore, water dissolves many salts of divalent cations like Mg2+, Ca2+, and anions like Cl, SO42-, HCO3 and CO32- for instance, plaster (CaSO4.2 H2O) and limestone (CaCO3). These salts make the water hard. Gypsum is moderately soluble in water, while limestone is insoluble in water. However, in the presence of CO2 small quantity of limestone is soluble in water according to the above chain reaction.

Types of Hardness of Water

Hardness is of 2 types:

  • (i) Temporary hardness is because of the presence of bicarbonates of calcium and magnesium.
  • (ii) Permanent hardness is because of the existence of sulphates and chlorides of calcium and magnesium.
Ways of Removing Hardness of Water

The elimination of Mg2+ and Ca2+ ions which are accountable for the hardness of water is called water softening.

Removal of temporary hardness

(a) By boiling

Temporary hardness of water can be easily eliminated by boiling the water. On boiling, calcium bicarbonate Ca (HCO3) 2 breaks down to produce insoluble calcium carbonate, which precipitates out of the water.



(b) Clark’s Method

A chemical technique to eliminate temporary hardness is by the addition of slaked lime Ca(OH)2. A calculated quantity of lime water is added to temporary hard water. Hence, once the magnesium and calcium ions precipitate out of the water, water becomes soft.



Removal of Permanent Hardness

Permanent hardness can just be removed by using chemicals. Calcium (Ca2+) and magnesium (Mg2+) can be eliminated of water as insoluble salts by adding washing soda (Na2CO3) or sodium zeolite.

By utilizing washing soda (Na2CO3)

The addition of washing soda can eliminate the calcium and magnesium ions as the insoluble calcium and magnesium carbonates, respectively.


By using Sodium Zeolite (an ion Exchanger)

Salt zeolite is a naturally occurring resin of salt aluminium silicate NaAl (SiO3)2, which can also be prepared synthetically. It is utilized for softening of water at domestic along with on industrial scale.


When water is gone through the resin, salt ions of the resin are exchanged with the unwanted


When the resin is fully used up it can be regenerated by flushing it with a concentrated amount of NaCl. The reverse procedure happens because of the high concentration of sodium ions.


Drawbacks of Hard Water
  • (i) Hard water takes in a large amount of soap in washing functions.
  • (ii) Drinking hard water causes stomach problems.
  • (iii) Hard water is unfit for usage in steam engines, boilers and turbines because insoluble calcium and magnesium salts deposit inside. They are called scales. They are bad conductors of heat and hence more fuel is used. Insoluble calcium and magnesium sulphates not only minimize the efficiency of the engine but likewise cause the boiler to burst.