Rubbing vaseline all over your feet, including between your toes, can help avoid blistering when feet get wet. I also noticed that when wearing compression socks, blistering is basically never an issue (but those don't make sense for everyone).

My solution is to use slightly smaller sock sizes, so that they are always stretched tightly around my foot, and there is minimum movement between the sock and my skin.

But also, correct shoe for your foot shape, so that everything is tight and snug in there, instead of moving all around - especially around toes, but also the heel.

I typically only get tiny blisters on longer runs - that's 40km or more for me. But that happens regardless of whether my feet get drenched or not. Of course, everyone's feet are different, so you have to find what works for you. :)