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It's the Law

Discharge of Waste

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

It is illegal to discharge raw (untreated) sewage into any public waters.

Public waters are classified as either "discharge" (capable of accepting treated sewage) or "no discharge" (waste must be retained in a holding tank and properly discharged on shore).

  • Discharge into public waters is restricted to Type I or II MSDs and only on those waters classified as "discharge."
  • The discharge and no discharge reservoirs are listed on the Tennessee's Reservoirs page.

All installed MSDs must be USCG–certified.

Marinas and docks operating on public waters must provide a sewage removal service.

Types of MSDs

There are three types of MSDs.

Types I and II 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.

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.

Marine Sanitation Device (MSD)
The Y valve must be secured so that waste cannot be discharged into the water.