Here is what a behind-the-ear hearing aid tube with moisture inside looks like:
See the water droplets inside? Not good. I remembered putting my hearing aid in right after the shower when I was running late for work. This is usually not a good idea if you want to avoid getting water on your hearing aid.
So I replaced this tube, it was time to change it anyway.
But, if your water droplet laden tube is not ready to be replaced and you want to get rid of the moisture, you can use one of these guys:
You use it to blow out the moisture in the hearing aid tube. It works pretty well.
Otherwise to avoid getting moisture in your hearing aid and its tube, don't wear your hearing aid in the rain, when you go to the beach or the pool, hang out in the sauna, and when your hair or ears are wet; common sense stuff.