What is the required oil content limit in water discharged through an oily water separator (OWS), and what must be documented?

• A. 5 ppm oil in water; the discharge must be in compliance and logged in the OWS/engine room records.
• B. 15 ppm oil in water; the discharge must be in compliance and logged in the OWS/engine room records.
• C. 0 ppm oil in water; the discharge must be logged in Garbage Record Book.
• D. 100 ppm oil in water; the discharge must be in compliance.

Answer: (B)

The main idea is that oily water separator discharges must meet a specific regulatory limit and be properly recorded. The oil content in water discharged through an OWS must not exceed 15 parts per million. This limit is set to protect the marine environment, per MARPOL Annex I. Along with meeting this limit, the discharge must be documented in the ship’s records—specifically the Oil Record Book (ORB) or the OWS/engine room records that log bilge water processing and any discharges. The purpose of the documentation is traceability for inspections and compliance verification. Garbage Record Book entries are not used for oily water discharges, and a 0 ppm requirement or a 100 ppm limit do not reflect the regulatory standard.