by Trackstriper » Fri Jan 09, 2009 8:59 pm
Bill,
This will be long but maybe it will help. I have a small "cubby hole" section in my work van that I can use as a camper when I'm out of town working solo. Something about Motelophobia. I have a sit-down, hot water shower with a small portable toilet to sit on...it serves dual use. I've been using this set up for about eight years now.
My first toilet was a Thetford Porta-Potti with the bellows water pump. This potty lasted through seven years of regular use. Finally the cover lid for the seat cracked and split. Tried repairing it but after a few poor attempts just got rid of the unit; the seals were probably about due for replacement anyway.
I bought a Dometic 740 series potty about six months ago. This one seems to be well built but I find that the seat is considerably smaller than the Thetford and doesn't fit me all that well...a little too small, and I'm not a big fellow. The (air) pump system on the Dometic pressurizes water in the upper flush water tank and a push button effects the flush. It does not flush as well or as controllably as the Thetford. The Thetford bellows system would allow for a very controlled quantity of water to be used for flushing. I may not toss out the Dometic, but I will buy a new Thetford for my trailer. Some of the Thetfords have a battery operated pump, I'd like to check that out, but the bellows was very good, and quiet.
My first reaction to a porta-potti was ....yech, double yech! How're ya gonna clean that thing? Oh, that's gotta be bad. Once you get used to the idea it's no big deal. I am often around high schools while doing my work and can often use the outdoor restroom facilities at the athletic fields as a place to dump. On the road, some of the truck stop style gas stations will have dumping facilities. At home I dump into the bathroom toilet. Turn on the fan...no problem. About the only place that I've received a "no" from, upon asking, was an actual campground...I wasn't a paying guest.
The chemicals that you use do make a difference. The formaldehyde based products are hard on my breathing, just being around them. I've tried a number of products and right now I'm happy with Oxy-Kem packets available at WallyWorld. A bit pricey, but no smell. In the cooler months the toilet can go for quite a while without maintenance (unless it fills up). In the hotter summer months I will have to take care of maintenance about once a week weather I've used the potty much or not. You can pretty well tell by the odors when you open the slide valve during use.
I basically have my potty in constant "use" so that it's there for me when the time is opportune. I would imagine that if you are camping for just a week or so at a clip, you could finally empty the unit when you got home, flush it out, add new chemicals and you'd be ready to go next time.
If you only have occasion to use it once a year maybe one of those dry bag systems would work better. I just have occasion to use mine a lot, it's a great invention, and not half as messy as it sounds.
Bruce
Good one Bruce. We have used ours when the plumber was needed. The only thing I will add again---if you can avoid it don't flush chemicals. They end up in someone's water..............
Must be what came with our porta we haven't been able to find again. 
