Marine Sanitation Devices

Recreational boats are not required to be equipped with a toilet. However, the “Clean Water Act” of 1972 (amended 1987) requires that if a toilet is installed, it must be equipped with an operable Marine Sanitation Device (MSD) that is certified by the Coast Guard. Installed toilets that are not equipped with an MSD, and that discharge raw sewage directly over the side, are illegal.

Portable toilets or "porta-potties" are not considered installed toilets and are not subject to the MSD regulations. But they are subject to disposal regulations that prohibit the disposal of raw sewage within territorial waters (3 mile limit), the Great Lakes, or navigable rivers.

 

MARPOL

It is illegal to dump:

Inside 3 miles and in U.S. Lakes, Rivers, Bays and Sounds
and anywhere on the Great Lakes no matter how far from shore:

Plastic, dunnage, lining, and packing materials that float
and any garbage except dishwater/graywater/fresh fish parts.

3 to 12 miles

Plastic, dunnage, lining, and packing materials that float
and any garbage not ground to less than one square inch.

12 to 25 miles

Plastic, dunnage, lining, and packing materials that float.

Outside 25 miles

Plastic