Wisconsin law states that it is unlawful to place, leave, or discharge waste or waste containers into or near any Wisconsin waters.
Every vessel with an installed toilet must have an operable marine sanitation device (MSD) on board.
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.
- 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.
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 USCG–certified.