why not? We use water based gel on them All the time :o It pretty much drowns in gel at a daily basis at my workplace. I have not encountered any probe that the tip or most part of the transducer is not made to survive water. You pretty much dip it in water every time you do any examination with it, arguably even worse since the gel leave that sticky dried thing afterwards. If it could get into the probe or do damage the equipment would deteriorate under normal use. Just dont dip the cord part. We even use water baths in the very beginning to practice with for needle postition and get a hang of the movement of the probe and needles/structures for surgery. The trick with water bath is an amazing tip.