I figured out the rebus portion of the puzzle pretty quickly today. I had 1A: Wise ones (SAGES) (gets a C+) and SASHA immediately, and then ATRIA. I looked at 3D: Somatotropin, e.g., knowing that was a GROWT[HHO]RMONE, but thinking: That doesn't fit. So I put in GROWTH____ and waited. Once I had KARATE in place, and ORONO / MAINE, I incorrectly put in GROWT[ho]RMONE and didn't notice the problem until later.
It was when I filled in the NE section and got CHANGEYOUR[H2O]WAYS (see what I did there?) that I went back and fixed my earlier mistake. The theme is clever, definitely. I like it a lot. The down answers read as a rebus for [HHO], while the across answers read that same rebus as [H20]. In addition, the across answers are common phrases with "water" added, and then clued wackily.
Some of these answers work much, much better than others. My favorite is definitely 95A: Conservative's opinion of the Republican presidential candidates? (GOODASGOLD[H2O]). Solid initial phrase, great twist when you add "water". Although from the recent news, I'd hazard to guess that a number of conservatives would disagree with this assessment of Donald Drumpf.
None of the other theme answers have the same Aha cleverness to them. SALT[H2O]OFTHEEARTH is pretty good, as is HOT[H2O]WIRES. On the other hand, DOGGY[H2O]BAG just has me quizzical. How is that a "Container to keep a canine cool?" Is the dog inside the bag? Is the dog drinking from the bag? A "water bag" is not something I'm familiar with.
I should also mention that the down rebuses are all strong examples of phrases with [HHO] in them, although the plural RUS[HHO]URS is less esthetically pleasing. JEWIS[HHO]LIDAY was the least expected.
I always love BACON. Just made a fine breakfast sandwich for my wife for Mother's day that contained lovely bacon. I use Coleman's, because the flavor is so fine. I also enjoyed 55A: How many a medical problem ends? (ITIS), but I imagine that your mileage may vary on this one.
On the downside, there were whole sections of fill I actively disliked. The SE corner, for example: plural NEALS, plural archaicism NAES, and never used plural ASYLA. Oof. Just above that: abbreviation of first name JAS, strangely plural STETS, never used exclamation YOWIE. Hmm.
I almost had an error: the last square I filled in was the cross of KROFT and REMI. I couldn't see the latter, thinking of hEMI, dEMI, or sEMI as references to a musical scale (not quite right, obviously). But I figured it out just in time.