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It's the Law

Discharge of Sewage and Waste


If you have a recreational vessel with installed toilet facilities, it must have an operable marine sanitation device (MSD) on board.

  • Vessels 65 feet long or less may use a Type I, II, or III MSD.
  • Vessels over 65 feet long must install a Type II or III MSD.

All installed devices must be U.S. Coast Guard–certified.

Types of MSDs

There are three types of MSDs.

Types I and II MSDs are usually found on large vessels. Waste is treated with special chemicals to kill bacteria before the waste is discharged. Types I and II MSDs with Y valves that would direct the waste overboard must be secured so that the valve cannot be opened. This can be done by placing a lock or non-reusable seal on the Y valve or by taking the handle off the Y valve in a closed position.

Type III MSDs provide no treatment and are either holding tanks or portable toilets. Collected waste should be taken ashore and disposed of in a pump-out station or onshore toilet.

Marine Sanitation Device (MSD)