The primary function of a Sewage Holding Tank on a ship is to:

• A. Store Sewage
• B. Hold Ballast Water
• C. Carry Fresh Water
• D. Contain Engine Oil

Answer: (A)

On ships, waste management requires confinement of wastewater. A Sewage Holding Tank is a sealed tank specifically designed to store sewage (blackwater and related wastewater) onboard until it can be discharged at a shore facility or treated aboard, in compliance with regulations such as MARPOL Annex IV. This setup prevents pollution by keeping sewage contained during the voyage or when discharging is restricted.

The other options describe different onboard systems: ballast water is kept in ballast tanks for stability, fresh water is stored in potable water tanks for drinking and hygiene, and engine oil is held in oil storage/ sump tanks for lubrication. The holding tank’s sole purpose is to store sewage.