Understanding Water Purity Methods

Water purification is the process of removing contaminants from water to make it safe for drinking or other uses. Impure water can contain various impurities, including suspended particles, dissolved substances, and microorganisms.

The Role of Alum in Water Purification

Alum, chemically known as potassium aluminum sulfate ($KAl(SO_4)_2 \cdot 12H_2O$), is commonly used in water treatment. Its primary function is as a coagulant.

• When added to impure water, alum helps neutralize the electrical charges on tiny suspended particles (like silt and clay).
• These particles normally repel each other and stay suspended, causing turbidity (cloudiness).
• Alum causes these particles to stick together, forming larger clumps called flocs.
• These larger flocs settle down more quickly or can be easily removed through filtration, thus clarifying the water.

The Role of Boiling in Water Purification

Boiling is a physical method used to kill harmful microorganisms present in water.

• Water needs to be boiled vigorously for at least one minute (longer at higher altitudes) to be effective.
• The high temperature denatures the proteins and enzymes essential for the survival of bacteria, viruses, and protozoa.
• This process disinfects the water, making it microbiologically safer to drink.

Combining Purification Methods

Since alum addresses suspended impurities and turbidity, while boiling addresses harmful microorganisms, using both methods significantly improves the purity and safety of water.

Therefore, impure water can be made purer and safer by adding alum (to remove suspended particles) and by boiling (to kill germs).