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.
...and to elaborate- a dump station is usually a concrete pad THAT SLOPES TO THE DRAIN, whereas at the campsite, there is usually not anything to address the situation if the pipe comes back out.
...and as one poster above has stated- there's a real risk of the slinky pulling out of the hole EVEN WITH a donut, so one needs use a bit of caution and common sense...you should really use a donut or threads regardless if it's a RULE or not- and even then a safety backup isn't a bad idea.