Water Composition, Hardness & Treatment

Understanding Water Hardness

Water hardness is determined by the concentration of calcium and magnesium ions in the water. These ions can cause various effects on water usage and appliances.

Types of Water Hardness

• Temporary Hardness: Caused by dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate). It can be removed by boiling the water.
• Permanent Hardness: Caused by dissolved sulfate or chloride compounds (calcium sulfate, magnesium sulfate, etc.). It cannot be removed by boiling.

Causes of Water Hardness

• Presence of calcium ions \\(\text{Ca}^{2+}\\) and magnesium ions \\(\text{Mg}^{2+}\\).
• Dissolution of limestone (calcium carbonate) and dolomite (calcium magnesium carbonate) in water.

Advantages and Disadvantages of Hard Water

Advantages	Disadvantages
Contains essential minerals beneficial for health.	Causes scale buildup in pipes and appliances.
Improves taste of drinking water.	Reduces efficiency of soaps and detergents.
May provide dietary calcium and magnesium.	Can lead to increased energy costs due to scale.

Methods of Removing Water Hardness

• Boiling: Effective for removing temporary hardness by precipitating bicarbonates as carbonates.
• Ion Exchange: Uses a resin to exchange calcium and magnesium ions with sodium or potassium ions, softening the water.
• Adding Washing Soda: Sodium carbonate reacts with calcium and magnesium ions to form insoluble carbonates, removing hardness.
• Lime Softening: Adding lime (calcium hydroxide) to precipitate calcium and magnesium as their respective carbonates.