For some reason I kept thinking Tums (Calcium carbonate), not bismuth (aka Pepto). If you're going to take one, take the bismuth - it can be used for upset stomach as well as tums, but has the additional anti microbrial properties. Like I said, it's not a "cure" medicine, but may help reduce the amount of bacteria causing illness. FYI, being a salicylate, people with allergies to aspirin/motrin/naproxen/NSAID's or stomach ulcers should avoid it.

Given that the water "isn't safe to drink" (Which, really, it probably is - given that the locals drink it, right? Just us tender Americanos have wimpy stomachs), how do you plan on treating it? You can use treated water with soap for cleaning. Antiseptic towlettes are OK for a quick and dirty clean, but they don't actually remove dirt or much particulate matter, they just kill whatever it touches. So you essentially have really germ free hands with dirt on them. Once that dirt dislodges, germs get exposed. Soap/water moves all that away. Better if you use hibiclens (or similar) or one of the anti-bacterial soaps. But even your basic 69-cent soap will clean better than a towlette, you just have to scrub.