NCEES Fundamentals of Engineering (FE) Environmental Practice Exam 2025 - Free Environmental FE Practice Questions and Study Guide

The three phases of water treatment, specifically in the context of surface water treatment, are coagulation, sedimentation, and filtration.

During coagulation, chemicals called coagulants are added to the water to facilitate the aggregation of small particles and impurities into larger clumps known as flocs. This is crucial because individual particles can be too small to be easily removed during subsequent processes.

Following coagulation, the water undergoes sedimentation. This phase utilizes the force of gravity to allow the heavier flocs to settle at the bottom of a sedimentation basin. The clear water that remains on top contains fewer impurities and is a critical step toward achieving clean water.

The final phase is filtration, where the water passes through various filter media, such as sand or granular activated carbon. This process effectively removes remaining fine particles, pathogens, and other contaminants from the water, delivering treated water that is much safer for consumption and use.

Together, these three phases ensure that water is adequately prepared for safe drinking and other uses, highlighting the importance of each step in the overall treatment process. The other choices represent processes that may occur in water treatment but do not accurately reflect the primary steps involved in the treatment of raw water for safety and cleanliness.