Cooling tower drift loss results in loss of which of the following?

• A. Vaporized humidity only
• B. Airborne minerals
• C. Heat energy without water loss
• D. Water droplets carried away with exhaust air

Answer: (D)

Drift loss refers to liquid water droplets from the cooling tower that are entrained in the exhaust air and carried away. This is a distinct form of water loss, separate from evaporation (vaporized humidity), and it directly reduces the amount of makeup water needed to replace losses. So the best description is water droplets carried away with exhaust air. While minerals in the water can be carried with those droplets, the loss itself is the water droplets in the plume, not just mineral content. The option about heat energy without water loss describes a different loss mechanism (not drift), and vaporized humidity is evaporation, not drift.