Not to be snide sounding....but coffee, tea, ice and fountain sodas are all made with local water. So if you avoiding local waters, shouldn't you be avoiding all sources of it? Including among other things fresh fruit and veggies (watered with it, and cleaned in it).
Well, when I read your words, I tried very hard to make them sound "not snide"

Naw, seriously, that's exactly what I was saying...I don't
drink the water when I travel, and if I take in too many other sources of local water -- beverages, ice, salad bars (yeah, I'd forgotten about that), then yep, it starts to bother me. Not that I'm gonna get Montezuma's Revenge in Orlando...just that I'm intolerant of a change in the water. But I'm not going to give up ice in my drinks, salads, or coffee (although I make coffee with bottled water our hotel room). I mentioned the water thing because what some folks might be thinking of as "food poisoning" might actually be a sensitivity to changing water.
Personally, I wish the immodium recommendations would stop. There is a time and place to take them. And it's not neccessarily at the first sign of a cramp or bathroom run. OK, gonna be blunt....if your body wants something expelled that badly, let it out. Generally (unless in a situation where stopping it is neccessary like there are no bathrooms- and Disney does not fit that description) diarrhea should be present for 24 hours typically before medicating for it.
Ummm...well...sheesh, how to put this gracefully.... I don't think it's been suggested at the "first sign" of anything. As for the time and place, well...if you are home in your own house, and you know for sure you aren't going to have to stand in line for a restroom, and if you aren't feeling really spiffy, can rest and relax, and you are sure you are going to be taking in plenty of fluids, then it's best to let nature take it's course, absolutely.
However...if you are on vacation, you only have a few days there and don't want to waste them sequestered in your hotel room...you are walking around in the hot Florida sun trying really hard to stay hydrated...and you can NOT risk that you will be too far from a bathroom...or you might be stuck in a line...or you might get to the bathroom and they have a line longer than the one for Space Mountain....

THEN you might want to have some immodium in your first aid kit

As well as Tums, bandaids, sunburn relief, etc.