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Under state law, toilets on board boats must be no-discharge devices (see exceptions below). Waste must be retained on board for proper disposal after returning to shore.

If you have a recreational boat with permanently installed toilet facilities, it must have an operable marine sanitation device (MSD) on board. All permanently installed devices must be U.S. Coast Guard–certified.

There are three types of MSDs.

  • Types I and II MSDs are usually found on large boats. Waste is treated with special chemicals to kill bacteria before the waste is discharged. Types I and II MSDs with “Y” valves that 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.
  • A Type III MSD, the simplest and most common, consists of holding tanks or portable toilets. It requires only a small storage space and is simple to operate. Type III MSDs have the least effect on the environment since the waste is to be discharged on shore into a local sewage treatment facility.

Type I and II USCG–certified treatment / discharge marine sanitation devices are currently legal only on the Mississippi River below Lock and Dam #2 (at Hastings) and on Lake Superior. This is a result of the federal preemption of state law. MSDs on boats less than 65 feet in length must be USCG–certified Type I or II devices.

Pumpout station
Marine Sanitation Device diagram