Today I decided to to not just drain but thoroughly clean and flush tanks.
So I drive to a Camp Sewer facility with plenty of time on my hands. I have 2019 Sunstar 29VE
I first setup and start to drain the black tank. While that was going on I drain the fresh water tank. My coach requires turning on water pump for fresh water to drain. After 10 minutes or so, I connect a fresh water hose to my black tank Sani Flush system. It must have run another 10 minutes, but all water was coming out of black tank was drinking fresh clear
So I open up the the gray tank and it starts to drain; so far all is good.
Eventually the fresh water stopped draining from fresh water tank. I then cut off and disconnected the hose to the sani flush. After 5 minutes all water had stopped; so I put up the sewer hose and prepared to drive back home.
But I tried some different
I left the low point drains lines open, thinking that the drive home may splash some more water to get in a position to drain out? I left both valves open for the gray & black tank, because I figure they were empty or just a little water residue may come out? But for good measures; I did put the sewer cap back on.
I drive home (15 minutes) and park. I decided to remove the sewer cap to let what I thought would be remnants of fresh water from sani flush hose, but noooooo, I got a big gush of black waste water
It was a lot of waste water; so much that I had to quickly put the sewer cap back on.
My question is where this all of this black waste water suddenly come from? That tank had been open for at least 5 minutes with nothing coming out?