We have this interesting problem with our dryer vent. The window well where it comes out is in a window well that tends to get a lot of water in a heavy rain. Sometimes, not very often, rain water fills up the window well and runs down the vent pipe into the dryer. We’ve taken the step sometimes when heavy rain is expected to pull the dryer away from the wall and disconnect the vent.
Last week when we had all of the rain, I actually found rain water (mud actually) in the dryer drum. It was full of clothes at the time, so I ended up with a bunch of muddy, wet clothes. We hired someone to take a look at the dryer; water had never gotten that high before. When he took it apart, there was no water in the dryer base, it was all in the drum. What happened was the mud came down the vent pipe, through the blower and out into the drum. The seals were tight enough that there was a very clear path for the water to go and we had no damage to the dryer. Weird.