My furnace stopped working, it had some read-outs saying the exhaust
was not working.
Turns out the exhaust pipe was full of water and filled the exhaust
fan with water.
I cleaned all of this out, but now I want to correct the problem.

My exhaust PVC travels from the furnace to the outside wall. There is
a belly in this pipe. Thats were the water was sitting.

Looks like I need to have it angled to drain back to the furnace - I
need to correct the belly.
Is there a standard size for this type of pipe? Mine looks to be 3"
dia. Rather large.