Sewage carries great amounts of waste. For this reason, it is illegal to discharge raw sewage and human waste from a boat within territorial oceanic waters (within the three-mile limit and 9 miles out in the Gulf of Mexico), navigable U.S. Rivers and the Great Lakes.

Though recreation vessels are not required to be equipped with a toilet, all boats that are fitted with a permanent toilet are required to be equipped with a U.S. Coast Guard-approved holding tank or sanitation device. Such approved and operable Marine Sanitation Devices (MSD) are instrumental in preventing pollution from human waste.

All recreational boats with installed toilet facilities must have an MSD on board.

Types of MSDs include:

• Type I and Type II– “Flow through” devices
• Type III– Holding tanks

Boats that measure less than 65 feet in length may use a Type I, II or III MSD. Vessels that are more than 65 feet long must install a Type II or III MSD. All installed devices must be certified by the U.S. Coast Guard and should be labeled as so.

No Discharge Zones

Boat operators are allowed to discharge sewage within 3 nautical miles of shore, except for in areas designated as “No Discharge Zones.”

As their name suggests, such zones are bodies of water where the discharge of treated or untreated sewage is strictly prohibited. When travelling within a “No Discharge Zone,” the operator must secure the device to prevent all discharge. To do so, a boater can:

• Use a non-releasable wire tie to hold overboard discharge valves closed
• Padlock overboard discharge valves in the closed position
• Close overboard discharge valves and remove the handle
• Lock the door to the enclosed toilet space

Untreated sewage may only be discharged beyond three nautical miles of the shoreline. Further restrictions on overboard discharges may be set forth by state or local laws.