STBRetired wrote:
The only thing like that under my bathroom sink is the siphon break / backflow preventer for my black tank flush line. Or are you referring to the air admittance valve (about 1 1/2" in diameter) on the drain line?
Black waste tank flush system.....
Anti-siphon vacuum breaker backflow device
Installed at least 2' above top of tank
Flush water comes up/in bottom of valve----pressure pushes a disc up closing off the top section which is open to atmosphere.
Flush water then goes out the side and down to flush nozzle in tank
If it leaks....replace it
Black ones are CHEAP (ie: JUNK)
Better ones are available
Clear plastic and Brass ones
Junk...
