The Maine Boater Safety Handbook
The Official Boating Handbook of the Maine Department of Natural Resources - Web Version
Table of Contents
If you have a recreational vessel with permanently installed toilet facilities, it must have an operable marine sanitation device (MSD) on board.
Vessels 65 feet or less in length may use a Type I, II, or III MSD. Vessels more than 65 feet in length must install a Type II or III MSD.
All installed devices must be U.S. Coast Guard-certified and working properly.
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.