I wouldn’t say it is unnecessary to avoid wet hair. I usually always do, this was a bit of a mistake because it was just the hair behind my ears that was damp. Normally whenever I wash my hair I dry it just for this reason. I have had aids for about 25 years, my first set was Resound, then I had a couple different Phonaks. I do like the Resound based on sound and the seamless integration with iphone and Streamer to Computer or TV, but now I recall I had this issue with my original pair of Resound. With in the first few months, the audi had to return them a couple times because I put them in after taking a shower and had wet hair! So I would say avoid water, but don’t give up if the aids fail! Let them dry, as Zebra mentioned 24 hours is a good recommendation. Mine where probably not that wet so they were functional after an hour or so.