3oaks wrote:
Some people are confusing a dump station straight pipe/metal capped pipe verses individual sites with sewer hook-ups (usually full hook-up sites), which require a sew donut or similar seal like the O.P. is inquiring about.
I don't think there is any confusion, unless you are assuming it always works the way you are explaining it.
We have both kinds around here at full hookup sites, heavy cast iron capped as well as threaded with a PVC cap. Threaded is more likely to be found at parking lot style RV parks whereas capped and un-threaded at campgrounds. Haven't needed the doughnut at either--nor at dedicated dump stations.
Mike