I do not believe any human will swallow mouthful of flood water on the road unless one is drowning. Further, I do not believe the story about your brother-in-law. Even if the flood water spilled on his lips or mouth, I am pretty much sure, he would have gone home and gargled his mouth. Currently in cities of India, just about any middle class family has access to a car, they have access to full vaccination schedule which would include one for infectious hepatitis, and they seldom drink tap water, almost always buying mineral water while traveling or boiling water at home.

People in cities, who are exposed to such GI infections are mostly low income people such as construction laborers. If you had said that your dhobi, electrician, plumber, or roadside vegetable vendor developed GI infection such as jaundice, I would believe your story, not if you say that happened to your brother-in-law. Someone who writes for New York Times would not have a brother in law who drives a scooter, and even if you had, you would habe been estranged from him long time ago.