Jennifer - is it the tan material with the holes in it? This will hold up well in the water as long as it's not warm water..lol...it melts pretty easily in lukewarm tub water. The foam will be ok because you can always rip it out and put in dry pieces while you rinse the old foam and let it dry on its own. But the problem is the velcro. Velcro strips comes off in the water!
We had a bathing splint made from Aquaplast for maia's last surgery and they put the velcro stips on there so I could use the regular strapping material but the velcro came right off in the water - even the heavy duty velcro - even after being glue gunned down and Gorilla Glued (waterproof glue) down, etc. I ended up having to ace wrap the whole thing on her and that worked fine (except that it took a long time for set up and taking it off.
I have pictures of her bathing splint on her site in the capsulodesis section. I think it's in here:
http://www.injurednewborn.com/maia/capsulodesis.html
btw - it was easy enough for her OT to make this splint - very worthwhile if you want to go swimming so that her regular splint stays intact.
good luck,
francine