I actually spoke with a Phonak rep today (I’m an Audiologist). She stated that the water resistance between the two companies are essentially the same, but the dust resistance is better compared to Siemens. These hearing aids work best if you use custom molds with the thick tubing and not open fit or receivers. With open fit or receivers, water can get in to the hearing aids through that tubing possibly and the receivers have electronics into it.
You have to send in the HAs to Siemens once a year to check the seals, however, that is not necessary with Phonak. The only thing they suggest is to have the mic protectors replaced once a year which can be done by your Audiologist or HIS.
Previously I stated that the Naida CRT aids shouldn’t be submerged under water because the receivers themself are not water resistance. The rep today stated that if you get a custom cShell made with the receivers you could technically go under water but she still advised that problems could occur.
Having the option of water resistance is great for hearing aids, however, they are not perfect yet. I am sure over the next few years, the technology will improve tremendously.