is your water tank full, or overfilling? this looks like an overflow tube...
it's one of your 'Low Point' drains that is not closed tight
'14 Thor Palazzo 33.3 compact diesel
KingTailgater2 Dish, 100w/5amps roof SOLAR, BlueOx, 100,000+mi since '14... US, Alaska, and Canada - Hiawassee,GA (and '14 Gulfstream Amerlite and '07 ForestRIver Rockwood) : )