We used a porta potty in a 18 wheeler for 8 years 1.5 million miles and never had a problem of having to burp it. I plan on getting one for the TC shower so in cold weather don't have to use water just like TW and I did for 8 years in the big rig. I'll tell you what the caribou 11m has so much more room than our big truck did. And we are still the best of friends. We used to tell single drivers meaning wife at home the best way to find out if you can get along in a big rig on the road is to spend the weekend in the bath room at home and if your still getting along after that go out truck driving together. Anyway I like the option of having both black tank and porta potty. Just my 2 cents