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It's the Law

Discharge of Waste


Houseboats must have a wastewater holding system to prevent the discharge of waste into the water. South Carolina law prohibits discharge of any sewage, treated or untreated, into the state’s freshwaters.

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