What is the function of a "Y" valve in a marine toilet system?

The function of a "Y" valve in a marine toilet system is to manage the disposal of waste by allowing it to either be directed to a holding tank or discharged directly into the water. This flexibility is essential for adhering to environmental regulations and for managing waste effectively while at sea. When a vessel is in designated areas where direct discharge may be prohibited, the valve can be adjusted to send waste to the holding tank for proper disposal at a shore facility. Conversely, in areas where discharge is allowed, the valve can be configured to directly release waste into the water. This dual functionality is crucial for ensuring compliance with marine sanitation laws and for maintaining healthy environments in marine ecosystems.