I will be sure to let you know if my service plan covers it. I think that is important. I had one with my Alfa, and found out that everything (everything) was "wear and tear" and that the insurance co. seldom paid out a cent. I got some money back on that contract. I was promised by Porters' RV in Coos Bay, OR that their policies were not like that. Will figure it out in a day or so. Meanwhile, I took your advice and put a hose into the toilet (rather than just using the clean out hose...this way I can clean out the pipes leading from toilet to black water tank. First I kept the valves open (not using gray water system) and the water coming out from the black water tank was very clear. Now I have the value to black water tank closed and I am not seeing a huge pouring out of water at the under belly. Maybe it has to go to a certain level in the black water tank to start coming out the under belly, which would mean some kind of leak in the black water tank (or it could be in a pipe of some kind).
Here is what I have since done (oops moment). I closed the black water and put the hose in the toilet. My oops moment is that I didn't realize it doesn't take long for the tank to fill....and went outside to look underneath at progress and realized there was water coming from lots of places. Turn off water and looked in bay and realize it was getting wet. Toilet was overflowing! My big mistake! Opened the black water and it was 85% clear water coming out. That is good. And the water out of the toiled was not that bad. Cleaned up a lot of stuff and am drying it out in basement with heaters.
So, what really is a quandary...,.apparently the black water tank filled up. So where was the original brown water coming from? Has to be a pipe? I really just wanted to clean out the black tank as you recommended (it is CLEAN) AND try to figure out where the leak is coming from. I know it is not the gray water system. And maybe not even the black water tank. A leaking pipe? Someone will obviously have to check it out next week. Meanwhile I think I can continue using my sinks, will use the park's shower amd toilet and my own portable toilet at night if necessary. Did I do good (other than letting toilet hose overflow)?