Considering
(i) Screening
(ii) Sedimentation
(iii) Disinfection
(iv) Filtration. . .

The correct sequence of treatments which are generally given to treat raw water supplies are

Explanation:

This sequence — Screening → Sedimentation → Filtration → Disinfection — is the standard flow in municipal and industrial water treatment plants.

Screening 

• The first step in water treatment.

• Removes large floating debris such as leaves, twigs, and other large particles from raw water.

• Prevents clogging and damage to downstream equipment.

Sedimentation

• Water is allowed to stand in sedimentation tanks so that suspended solids settle at the bottom.

• Reduces the load on the filtration system by removing heavier particles.

• Enhances clarity and prepares the water for more refined treatment.

 Additional Information

Filtration 

• The settled water is passed through filters (commonly sand or multimedia filters) to remove finer suspended particles.

• Further improves the clarity of the water.

• Critical for ensuring the effectiveness of the next stage, disinfection.

Disinfection 

• Final step to kill or inactivate pathogens (bacteria, viruses, protozoa).

• Usually achieved through chlorination, UV treatment, or ozonation.

• Ensures the water is safe for human consumption.