Water carried in vessel tanks for stability.
- dirty ballast: ballast water that contains residual oil. When seawater is introduced into empty cargo tanks, residual oil mixes with the water and requires special handling at sea or treatment at a specialized facility before being discharged into the sea. Dirty ballast consists of seawater contaminated with approximately 1% crude oil.
- clean ballast: ballast water that is essentially free from oil. Does not exceed 15 ppm total recoverable oil and grease (TROG) and does not exceed 15 ppb benzene, toluene, ethylbenzene, and xylene (BTEX).
- segregated ballast: ballast water that is in tanks designed and used exclusively for that purpose.