Marine Sanitation Devices (MSD)
Marine Sanitation Devices and the related requirements & laws are control under 33 CFR 159
Marine Sanitation
All recreational boats with installed toilet facilities must have an operable Marine Sanitation Device (MSD) on board. Vessels 64 feet and under may use a Type I, II, or III MSD. Type I and Type II are "flow-through" devices, while a holding take is a Type III device. Vessels over 65 feet must install a Type II or III MSD. All installed MSDs must be U.S Coast Guard-certified, U.S .Coast Guard-certified devices are so labeled, except for some holding tanks, which are certified by definition under the regulations.
The discharge of treated sewage is allowed within 3 nautical miles of shore except in designated "No Discharge Zone" areas. (Untreated sewage may be discharged beyond 3 nautical miles.) All inland lakes, waterways, rivers streams, the Great Lakes and another inland waterway the United States has control over is a "No Discharge Zone" unless otherwise marked.
A "No Discharge Zone" is a body of water where the discharge of treated or untreated sewage is prohibited. When operating a vessel in a No Discharge Zone, the operator must secure the device in a manner that prevents any discharge. Some acceptable methods are: padlocking overboard discharge valves in the closed position, using a non-releasable wire tire to hold overboard discharge valves and removing the handle, and locking the door to the space enclosing the toilets. Note: these methods for preventing the overboard discharge are only required when operating in a No Discharge Zone. State and local laws may place further restrictions on overboard discharges.
Locked & closed Y Vavle
Required to be the one, of a number of places where a locking device shall be placed in No Discharge Zones
Shoreline Pump Out Station
Example of a pump out station that may be found on the shore, or in some locations, floating stations.
