Re: rv potties 101
RV Toilets are different for a variety of reasons, and the China Bowls you see in the big dollar rigs are still RV toilets, but they are made of nicer stuff.
Water volumn is the one of the keys as mentioned above, you have a limited amount of waste tank capacity, and as such you don't want the black tank topping out after a few days at the campground. As they are right now, very little watere goes down the drain, the toilet bowl itself only holds a couple quarts of water. Typically you won't fill the bowl when flushing anyway, you just use a cup or two at the most... At that rate it'll take quite a bit of use to fill a 30 gallon tank! That is good, because you certainly don't want to have to break down and take the bus to the dump station every other day to empty the tanks.
Now, they do indeed dump directly into the black tank, but the toilet itself has a gate valve at the bottom of the bowl, this is to keep water & waste in the bowl until ready to flush, as well as to keep the oders from wafting upwards into the living area of your bus.
Additiionally, the gated toilet (as compared with a house type with a bottom trap) again prevents oders from wafting up into the cabin while in transit. If you put in a regular house toilet with a trap, and that water sloshes around enough...you're going to have a big mess on your hands (actually on your floor) when you finally get to where you are going. Now if you flush and empty the tank first, then the trap will slosh around until it is empty, then the oders will not just waft back at you, but because you are going down the road at hiway speed, and there is a vent stack from the tank to the roof, the forced air going down that vent stack is now free to fill the interior of your bus with some very unpleasant oders...BIG TIME!
We can also add that a regular house type toilet will not meet DOT spec's either, but there is an abundance of bus converters out there that tend to ignore DOT specs...
You just might be a Redneck if...
...your motor home used to be a school bus!
...Your living room has a steering wheel!
...Your home has brake lights
1994 Jeep Grand Cherokee
1989 Thomas Diesel Pusher (Cat 3208/Freightliner)