Which of the following is NOT a public water treatment step?

• A. Screening
• B. Distribution
• C. Sedimentation
• D. Filtration

Answer: (B)

The main concept tested here is distinguishing actions that actually treat water from those that simply deliver it. Screening, sedimentation, and filtration are classic treatment steps: screening removes large debris early in the process, sedimentation lets suspended solids settle so they can be removed, and filtration removes smaller particles to improve clarity and reduce contaminants. Distribution, by contrast, is the system that delivers the treated water to customers and maintains pressure and storage; it does not itself alter the water’s quality through treatment processes. So distribution is not a treatment step, making it the correct choice.