Which step typically follows coagulation/flocculation in public water treatment?

• A. Sedimentation
• B. Screening
• C. Disinfection added
• D. Distribution

Answer: (A)

After coagulation and flocculation, the formed flocs are removed by gravity in sedimentation basins (clarifiers). This step lets the larger, heavier particles settle to the bottom, drastically reducing turbidity and the amount of suspended solids entering downstream processes. With the solids settled out, the water is much clearer, which makes subsequent filtration more effective and helps ensure the disinfectant can work more efficiently later on. Screening, as a debris-removal step, typically happens earlier to eliminate large objects before treatment begins. Disinfection is usually added after filtration, and distribution occurs after the water has been treated and made safe for use.