Are you saying it's filling up with "waste", or is it just water?
If it's water I'm thinking the water isn't stopping when you take your foot off the pedal. I.E. does it fill up by itself?
Disclaimer; I know next to nothing about this stuff, but you seem at wit's end so I'm just throwing thoughts out there.
If age is a state of mind, and I've lost my mind, I'm AGELESS, right?
Give me 40 acres and I'll turn this rig around:
Flagstaff 5er 2014 8528 IKWS
, Platinum Package, Regency Interior "Buffy"
F250 Super Duty 2013
Tuxedo Black "Biff"
Days camped 2014