Lynnmor wrote:
therink wrote:
Look under bathroom sink. The backflow preventer is usually way up behind the plumbing for the bathroom sink.
The above is a drain vent.
There is probably a check valve where the hose attaches to the trailer that is stuck. A vacuum break is usually installed inside the trailer near the point of entry, but that is unlikely the cause of no water flow.
Not true, the black tank flush has a backflow preventer between the outside flush connection and the black tank. It has nothing to do with a vacuum breaker (found on the vents of some gray water tanks).