🔍 Key Concepts

• MARPOL and 33 CFR rules on oil pollution and overboard discharges • The difference between ballast in cargo tanks and segregated ballast tanks • Typical sources of oily mixtures onboard (bilges, pumprooms, machinery spaces)

💭 Think About

• Which of these locations or liquids is specifically designed so it should NOT normally contain oil or oily residues? • Think about where oil is routinely present during normal operations and where it is not supposed to be present. • If you opened the overboard valve from each of these systems, which one would you expect to have the cleanest water from a pollution-control standpoint?

✅ Before You Answer

• Verify which system is completely separate from cargo and fuel oil systems by design. • Identify which listed liquids are usually classified as oily mixtures that must go through an oily-water separator or be retained on board. • Check MARPOL/33 CFR guidance on what qualifies as clean ballast that may be discharged directly overboard under normal conditions.