International Telstar Owners Association

During pump out, should the lever in the head be in the "holding tank" position or the "thru hull" position?

Has anyone heard of a holding tank developing cracks because of imploding during pump out? I had a dock worker tell me that and a question it.

Alan

Yes it is possible that the holding tank can implode. The much more likely event is for the pump out not to complete.

The cause is a blocked vent, usually caused by an overfilled tank. I don't see how the position of the head pump would have any effect. Even on dry bowl, the pump would block air passage.