I have used a Tagaderm (4 x 43/4") transparent dressing from day one. I place it over the bandage that they put on at the center. It's never gotten wet but I use a spray nozzle in the tub and not a shower. I am looking forward to the day I can stand in a hot shower for a long time! A very nice nurse gave me a bunch of the Tagaderm dressings in the hospital and thereafter, every time I was back there for my numerous appts and procedures, I'd always ask for as many as they could spare. (It never hurts to ask right?) They always gave me a few to several. I finally used my last one yesterday and went to price them today at a medical supply store. They are almost $5.00 for one single dressing!!
I went to Walgreens and bought some waterproof Nexcare sport pads and Johnson & Johnson waterproof pads for about $1 each. Smaller but hopefully will do the trick.