^^ I use electrical tape on most of my wheels (even a tubeless pair) and that holds up fine for years at a time.
Pretty much all rims have a dead space in them where water will eventually seep into it, the key thing is the tightness of the bead against the rim, as some will allow the water to drain right back out, others might take a few days, and once it gets into weeks its basically never coming out!
^^ I use electrical tape on most of my wheels (even a tubeless pair) and that holds up fine for years at a time.
Pretty much all rims have a dead space in them where water will eventually seep into it, the key thing is the tightness of the bead against the rim, as some will allow the water to drain right back out, others might take a few days, and once it gets into weeks its basically never coming out!