Question: Does a vessel with an Lectrasan need to have the overboard Y valve closed or can it discharge treated material directly overboard?
Answer: The Lectra San Type I Marine Sanitation Device (MSD) is an innovative USCG-approved secondary sewage treatment system that allows a user to treat and discharge head waste in all but specified "zero discharge zones".
Many boaters find that they must regularly dose the holding tank with harsh chemicals to dissipate offensive odors, and often, due to lack of or inoperative pump-out stations, they end up discharging the harmful contents directly overboard.
Onboard treatment via a Type I MSD means that, in most bays and coastal areas, waste does not have to be retained in a holding tank. The overboard disposal of treated effluent has proven to be a realistic alternative for many boaters interested in fewer visits to pump-out stations. With this technology you can be environmentally responsible and compliant with all but "zero discharge zone" regulations, and with a twist of the Y-valve, the holding tank can be put back into use making the vessel fully compliant.
Federal and Local regulations determine whether treated sewage can be pumped overboard or into holding tank. Ensure holding tank is empty, prior to operating in restricted pumping areas.
So the answer is they still need a method of prohibiting accidental discharge.