Which of the following methods is commonly used to remove suspended impurities from water?

Step 1: Analyze the question The question asks which method is commonly used to remove suspended impurities from water. Suspended impurities are insoluble solid particles (sand, silt, clay, debris) that float in or are carried by the water but are not dissolved in it.

Step 2: Explain the concept Suspended particles are large enough to be physically trapped. So the best method is one that separates solids from liquids using a barrier, which is filtration.

Step 3: Evaluate each option

• A. Fluoridation: Adding fluoride to water to prevent tooth decay. It removes nothing.
• B. Chlorination: Adding chlorine to kill germs (bacteria and other microorganisms). It disinfects the water but does not remove suspended solids.
• C. Filtration: Passing water through a porous medium (sand, gravel, filter paper, or cloth) that traps suspended solids and lets the water through. This is correct.
• D. Distillation: Boiling water and condensing the steam. It removes dissolved impurities and gives very pure water, but it is expensive and not the common method for removing suspended solids. Filtration is the standard method in water treatment.

Step 4: Answer The correct option is **C.

Water treatment order (useful for exams): Screening → Sedimentation (with coagulation, e.g. alum) → Filtration → Chlorination → Storage and distribution.

Exam tip: Match the impurity to the method:

• Suspended solids → Filtration
• Germs → Chlorination
• Dissolved salts → Distillation
• Tooth protection → Fluoridation

Remember "suspended = filter."