[cosmie]

At least in many cases, it's grounded in reality. For example, traveler's diarrhea[1] and hepatitis A[2] are fairly common for Westerns traveling. Hep A isn't a serious issue for locals, because of exposure from childhood - it's similar to how Westerners (in the US, at least) get the chickenpox as children, then rarely have it again in adulthood. But if they get it in adulthood, it's usually far more serious/complicated than the childhood variant. You're very likely to get exposure to Hep A if traveling to many countries, and if you haven't had a vaccination for it then you'll have a pretty crappy time of things as your body gets introduced to something that historically your body has been around since birth.

Hence recommending bottled water, as a precaution to prevent exposure. However, in reality everything around you has been washed, cleaned, laundered, or cooked in local water. And your shower/bath will not be in bottled water. So your exposure is still there, just lessened. Not to mention people that drink bottled water, but poor it into a glass of ice (which was created from non-bottled, local water).

[1] https://www.mayoclinic.org/diseases-conditions/travelers-dia... [2] https://wwwnc.cdc.gov/travel/diseases/hepatitis-a

[1] https://www.mayoclinic.org/diseases-conditions/travelers-dia...