FIXING THE BLACK / GRAY VENT LINE ON AN AIRSTREAM INTERSTATE

Much to our exasperation, we recently discovered the same apparent design flaw with our black water tank as took us quite some time to DIY-re-engineer with our gray water tank (see launch page for that project here).

As with the gray water tank, the black water tank's vent had completely separated from the tank.  That aqua blue staining you see around the pipe is toilet treatment having sloshed up and out through the resulting split.  To the adjacent left of this photo is the electrical converter, which is the very last place in the motorhome where one would want to have free water flowing.  Especially black water.  

Furthermore the joint looked... odd.  Like it had been coated up with multiple materials.  

I have no idea how Airstream was trying to attach this pipe or why they were using the method(s) that they did.  

Anyway, this was a pretty quick fix for us specifically because we had spent so much time and effort fixing our gray water tank.  In many respects, it was same "stuff", different day.

As with the gray water tank, the entire pipe assemblage was inflexible, which we believe contributed to the breakage (it should bend, not break).  Here you see a green and black measuring tape holding up the Pex water lines, which were resting on top of the tank.  We didn't want to un-do the lines, so we just worked around them.  My husband is using a large pipe cutter to simply chop out this entire section of pipe.  

Very challenging working conditions, obviously.  On our model of Interstate, the gray water tank is slung beneath the chassis, but the black water tank is located inside, right behind the commode and underneath the refrigerator.  

Here is the scene with the joint section cut away.  

To make a long story short, we cleaned up the port in the black water tank much the same way we had done for the gray water tank, and added the same type of rubber gasket at the join.  And then, because this was simply an air vent that would be relatively insensitive to pipe configuration, we fabbed a repair using common materials, including a flexible splitter.

You would never do this for a liquid connection, but this is just an air vent.  That new section in the middle is made of rubber, which will flex.  Below the PVC pipe spliced in, there is another rubber fitting.  Bend, don't break.  That is our RV mantra.  

So there you have it - yet another P.I.T.A. taken care of.  This time, a rather literal P.I.T.A.