1970's Argosy trailers with a front gaucho commonly have the water tank above the floor and under the gaucho at the very front of the trailer. If you have a water filler door
like this one under your front window, I've got to add one more gasket for us all to check.
I have replaced the front 4' of my floor due to rot from a leaking wraparound window frame. I've Rot-Doctored and epoxy coated the most hidden areas of the new floor under the tank. I'm very close to reinstalling the water tank, pump and gaucho. While leak testing the exterior yesterday I experienced a flood from leakage around the water filler door. The gray plastic molding inside the filler door acts like a funnel, channeling the water to a pipe-clamped hose attached to a filler tube on top of the tank.
It turns out there is a hardened foam gasket on the perimeter of the water filler door that has long since lost its seal (photo below). This is the ONLY barrier to rain water and road spray entering the fresh water tank! I don't know the material or thickness before it was squished to less than 1/8". Guess I'll be looking around for a closed-cell substitute. A number of better fixes come to mind.
If you think gasoline can get old, you wouldn't believe the algae gobs and green water I flushed out before I considered basic tank cleanup complete. I'll pay for gallons of spring water around the country before I feel comfortable drinking out of my fresh water system. Nothing beats constant use and regular flushing to maintain a clean system. Various threads have been around on periodic maintenance -- do searches on 'potable water' or 'bleach' ... and on and on.
Anybody else dealt with a similar door on their Airstream or Argosy?