Forum Discussion
gotsmart
Nov 14, 2014Explorer
If you have a sink that drains into the black tank then it should have one of these vents downstream of the P-trap. It keeps the water from being sucked out of the P-trap when you dump the black tank. It is also a source of air intake for the roof vent (other than flushing the toilet) to help draw the sewer gases out of the holding tank.


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