How are holding tanks plumbed?

Thanks all.

I upgraded my black tank, tank grommet and the idiots slathered it with white dicor mess as well. It may depend on tank material, the grommets are usual with PE tanks, the ABS tanks have spin on fittings if I remember correctly.

I'd say be prepared for anything, including drains plumbed into vent lines...

This is how many RV tanks are connected to the plumbing:Tank Grommet
They do come in other sizes.

Matt

Every manufacturer is different, but I doubt if it's a slip fit with a gasket. Too great a chance of leaks/odor.

Better plan on cutting the pipe(s).

According to the plumbing diagram from Winnebago, MY rig has one pipe plumbed into the top of the grey tank, the vent pipe. The kitchen sink drain T's into that pipe, and the shower drain T's into the sink's drain pipe before it gets to the vent. (My bathroom sink is plumbed into the black tank.)

Yours may have 1 (plumbed like mine), 2 (vent and sink(s)/shower), 3 (vent, sink(s), shower), or even 4 (vent, kitchen sink, bathroom sink, shower).

Most I've seen are glued and screwed.