Hacks to prevent travelers diarrhea?

I've traveled out of my country 3 times. All 3 times I've gotten sick with the poops. First time was when I had just arrived (pretty much ruined my trip) 2nd time it was later in the week, closer to coming home. And this last time as soon as I got home (improvement, yay!). I'm traveling to Europe in a few months and would LOVE to enjoy my entire time while I'm there. Any advice on what I can do so I stop the poops before they happen or am I just shit out of luck? 😉

I've learned NOT to use their water even for brushing my teeth, but what else am I doing wrong?