The water is unsanitary because most of the world's water IS unsanitary! Like Jesus, do you honesty think water in the world is magically clean and safe for human consumption provided that there's not a high level of humans around? Are you unaware of just how much **** goes into actually making water drinkable in developed and developing nations alike? It's more prominent in developed nations due to a stable country being well........stable enough to help provide it's citizens safe water and food. Wars, shoddy economy and/or a government that is either corrupt to the bone or prone to being torn down every few days doesn't usually have time, money or sometimes even cares enough to ensure it's citizens are semi healthy.
In developed nations the government, though can be corrupt, is usually more at the mercy of public opinion. It is therefore usually a good enough incentive to ensure it's citizens are semi healthy, aren't dying in droves and live long lives so they can vote for them for years.
So the government will provide it's citizens (a good majority of them anyway) with resources through government run programs/strategies designed to provide safe products for public consumption. Dams, infrastructure, sewers, treatment facilities and other facilities pretty much ensure that our water is drinkable and without all that nature-y goodness that will probably kill you.
Also you do know that there are literally deadly strains of the flu, right? What you want to freaking die?
