While I am willing to concede cassettes may have some advantage when not in a campground with full hook-ups, how long does it take before you become skilled at lifting a 40 pound tank of sloshing poo chest high out of the opening on the camper and dumping it into the tidy opening at your site in commercial campgrounds.

And the door to the darn tank only comes with one key. Called Thetford and was told that is how is shipped. If you want a second key they recommended I search the Internet for the appropriate Triumph motorcycle key blank and have it cut to match my existing (helpful hint here, the blank in the number series on your key is a reverse blank, it will not match.) However, if I order a new door only it comes with two keys. Huh?

So probably being odd man out, I hate the darn thing. Would rip it out in a heartbeat if I could see s reason way to plumb in a traditional two tank system.

 

While the answer to your primary question may not be what you want to hear, it is: MOST LIKELY NEVER ...You are not the odd man out by a long shot! Getting one out of the RV can't be as bad as lifting it up out of the head in the cuddy cabin on a boat, through a door intentionally put on backwards, which blocks the path to the deck when open and does not give you enough space to back up to close it while holding said sloshing pool of poop, and then up through the cabin door onto the deck, then over the side of the gunnel while dealing with the freeboard and trying to get it to ground / dock level all the while your wife is standing back at a safe distance "coaching". Then, just about the time you have stabilized the sloshing poo chest (for the 10th time), the boat is rocked again by a wave or by a big wake from a passing boat and...

I often times ask what ever was so wrong with the bucket or the old bed pan - chamber pots!

 

Well... nobody makes you fill up the cassette all the way. If you make it your routine to dump (and rinse) it every day, it will usually be much lighter.

Not even a tank deodorant needed, which means you can dump into any toilet in good conscience.

There are only two of us traveling, and we hardly stay in the same place for more than two nights. If you are used to parking it for a whole week, or the whole extended family is using the toilet, a fixed black tank may be more useful.

I actually do not know if we have one key or more. We usually do not lock that compartment.

 

yes it is lighter when partially full, but where you dump makes a hugh difference as does how long you stay. Sometimes we move around, sometimes we stay put for a week. Living in the Southeast means we dry camp and may have full hookups.

And as you know, you have to be on target as soon as you tip the tank or it overshoots the hole. Where we are now in a state park with full hookups, the hole is the standard RV connection about three to four inches above ground with a concrete barrier higher than the hole built around it. If you miss, all the slop is nicely contained in a perfect poo pool until it evaporates or the poo pool is filled high enough to run into the dump hole.

I think a cassette is a greater advantage when dry camping, otherwise not so much.

And the key thing just makes no sense at all to me.

 

No toilet concept is a one-size-fits-all solution.

Full hookup campgrounds of the type commonly found in North America basically do not exist here in Europe. And not all campgrounds over here even have the necessary facilities to dump a regular US black tank (as in: a hole in the ground that you can drive near). Cassettes, otoh, are very easy to dump. So that is a difference right there.

We had both systems and I find the cassette hugely more convenient. They are everywhere here, I don't know if any of the local RV builders even offer a fixed black tank.

Composting toilets are slowly getting more popular, but I have not had a chance to try one out so far.

Our (US made and shipped here) Northstar came with a Thetford cassette and two Thetford keys - I have checked. So maybe the person that gave the single key information was just too lazy to get off their chair.

ETA: you have a Northstar, right? I think they even let you order a fixed black tank instead of the cassette, at least in some of their campers. Of course, if you buy from a dealer's lot, you have no choice.