Boat Anti Siphon Valve

anti siphon
A device that prevents waste water from being drawn back into supply lines and possibly contaminating the water supply.
Preventive device for the backflow of liquid into a system. Used on sprinkler systems to prevent water from trickling back into the supply that is feeding it.

valve
A cylindrical mechanism in a brass instrument that, when depressed or turned, admits air into different sections of tubing and so extends the range of available notes
control consisting of a mechanical device for controlling the flow of a fluid
device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it
A device for controlling the passage of fluid through a pipe or duct, esp. an automatic device allowing movement in one direction only
A membranous fold in a hollow organ or tubular structure, such as a blood vessel or the digestive tract, that maintains the flow of the contents in one direction by closing in response to any pressure from reverse flow

boat
gravy boat: a dish (often boat-shaped) for serving gravy or sauce
A small vessel propelled on water by oars, sails, or an engine
A serving dish in the shape of a boat
a small vessel for travel on water
ride in a boat on water
(in general use) A ship of any size