The adhesive is the method of estrogen delivery, so it's not good if *large* stretches of patch come unattached to the skin. However, those little crinkles are normal (because people are bendy) and the manufacturer takes it into account when judging the dose to infuse the patch with. Water getting underneath is also only a problem if it causes the patch to come unattached; otherwise, the worst that will happen is a tiny bit of adhesive plus estrogen will wash off. However, all the patches have an extra cushion built in when it comes to dose, because, again, they assume some will be wasted/unused when it's being used on actual people.
(Basically, they know how much human skin can absorb per minute, and they add in that much plus a little extra just in case - which cannot be used by the person as it exceeds the skin's absorption rate, but is there in case of small incidents like water or chafing, etc.)
If you're really worried, I see a lot of recommendations to cover it with a Tegaderm waterproof patch for showering and bathing. Personally, I never bothered, and never had a problem.