Found something else that might be useful. A company called Hal-Hen that’s been around since the 1940s makes hearing aid accessories. They have a product called Super Seal for BTEs. It’s a water proof protective sleeve you can put on a BTE. I don’t think they sell directly to consumers so their products would have to be ordered through a hearing aid dispenser or audiologist. http://www.halhen.com/cgi-bin/info.cgi?id=2996&ls=sw~seals