There are six reasons why the United States and other "Western" nations do not consider clean drinking water as a basic human right, and correctly so. This, by in large, separates these nations from those for whom clean drinking water has been guaranteed by their selected form of governments.
First, while water is a vital necessity for life on this planet Earth, it is a resource not evenly distributed among all the lands on the planet itself i.e., some places have more than others. Certainly throughout history, when water sources had dried up or waned, the people that had the land where the water dried, more often than not moved or attempted to move where there was a water source a new river, a new lake, a new sea, vast oceans.
Such is the case with nomadic tribes in Africa and South America, even today. Many of those governments in Africa and South America are either dictatorships, inherently Socialist or Communist, where liberty is the commodity deigned to the people from the whims of the all-powerful government.
Where this differs from the modus operandi of the United States is that the locus of liberty, at least for the moment, rests in the stewardship and the balance of the people and the artifices of government boorishness against that stewardship held back.
Second, the term "right" means something different than for what it was intended by the Founders of the Constitution. The Founders understood that any government given too much latitude over the liberties of people will always seek to abridge those same liberties.
The term "right," as it is defined today, is something that from the government some citizens believe that they are entitled to, without recourse of payment or consideration. In other words, there are some segments of the population of the United States that feels like they are "owed" for the things they lay a claim on.
Similar dispositions have strongholds in heavily-socialist countries like Sweden and France. To correct the modern interpretation of the term "right," a right is something that preserves three inalienable ideals (life, liberty, property ownership) necessary for the prosperity of a people from the auspices of government control.
Hence, water is not supposed to be under the predilection of the government. The third reason begins with a question, "Who determines what is considered clean?" If individuals are capable of making that decision on their own merits, their own observations, and of their own will, then the individual is empowered, and responsible for the decision he/she has made.
Increasingly, we Americans have dropped the ball and allowed government to make our decisions for us - a bad trend to be sure. Why should we let a government that does not have our interests in mind, make small, vital decisions about water for us?
Fourth, there is the issue of sovereignty. We in the United States take pride in attempting to define what it is to be an American. We achieved those values from the bequests of those same Founding Fathers as came up with the Declaration of Independence and the Constitution. But there are the global, one-world government socialists that view such nationalism as arrogance, and with resentment.
Are the people that lack clean water supplies going to invade the United States or its northern neighbor Canada because there's so much more there than where they're at? Karl Marx and Friedrich Engels had a similar idea: "From each according to his ability, to each according to his need."
Making clean water a "basic human right" declares that no matter where someone lives, they are "entitled" to clean, drinking water, that they are not required to provide for the means to get it, that they just get it from those who have it. That's called wealth redistribution, or Marxism.
How does that provide for everyone, when the providers in this case, the nations that have abundant water supplies are the ones being damned simply for having?
Fifth, water is a survival instinct. Know how to find water, and it could save your life. Declaring "clean water" a human right reduces the capacity of people to look for water when survival is at stake. Finally, there is the comparison to "civilized Europe." Really?!?
Turn back the calendar 1,000 years to discover why the European water supplies are contaminated some even to this day beyond "drinkability." While it is true that clean water may taste the same, water itself cannot be declared a human right if we value freedom.