Difference Between Hard Water and Soft Water

Water is considered the elixir of life. It is an inorganic chemical substance containing hydrogen and oxygen in a 2:1 ratio. It has no colour, no odour and is transparent. Water is neither acidic nor basic. It is a universal solvent. The underground water from deep wells and rainwater has some properties that are different from each other. Based on that difference, water can be of two types hard water and soft water. In this topic, we are studying details about hard water and soft water and the differences between hard water and soft water.

Hard Water

Hard water contains deposition of carbonate, bicarbonate and sulfate salt of calcium and magnesium. These high mineral content make water hard. The common magnesium mineral in hard water is dolomite, and calcite and gypsum are the major calcium minerals. Drinking hard water may not cause damage to the body. In contrast to that, it has some health benefits too. The health benefits are due to the presence of calcium and magnesium ions which are essential to our body.

The hardness of water is of two types. Permanent hardness and temporary hardness. The permanent hardness of water is due to the chloride or sulfate ions of calcium and magnesium. These can not be removed by boiling. Temporary hardness is caused by soluble minerals of carbonate, calcium and magnesium. Boiling helps to remove the carbonate and bicarbonate salt of calcium and magnesium. Permanent hardness can be removed by using a water softener or an ion exchange column.

Reasons for Hardness of Water

Deposition of calcium and magnesium salts make the water hard. The anions may be chloride, sulfate, carbonate and bicarbonate. Chloride and sulfate salts may not precipitate out even at higher temperatures. But carbonate and bicarbonate salts will precipitate on boiling. When soap is mixed with it, it forms scum rather than a lather. Hence hard water is not suitable for cleansing.

Removal of Hardness of Water

There are a number of methods to remove hardness from water. It includes boiling water, adding washing or slaked lime, adding Calgon or sodium metaphosphate, or using ion exchange resin. In the Calgon process, when Calgon is added to hard water, it displaces calcium and magnesium ions by sodium from the anion of the Calgon and forms a complex.

Soft Water

Soft water is surface water which contains low concentrations of calcium and magnesium minerals. Chemically softened water is also called soft water, which contains a high amount of sodium ions. Soft water tastes salty while drinking.

Differences Between Hard Water and Soft Water

Hard water and soft water can not be differentiated by touch or appearance. These are differentiated based on their mineral contents. The major differences between hard and soft water are listed below.

Interesting Facts

• On Earth, the same amount of water is present as it was present when Earth was formed.

• 75% of the human brain contains water, and 75% of a living tree contains water.

• The water of human faucets could contain molecules that dinosaurs drank.

• Humans can live a month without food but only one week without water.

Key Features

• Hard water is the water containing a high amount of minerals of calcium and magnesium

• Soft water is the surface water or chemically softened water

• The main difference between hard water and soft water is that hard water does not form lather with soap, but soft water forms bubbly lather with soap

• Hard water can not be used for cleaning, but soft water can be used for cleaning.

• Deep underground water in wells is an example of hard water, whereas rainwater is soft.