Most of North America, the tap water is perfectly drinkable; but it can still be improved with extra filtration.

These also provide water colder than a tap can.

To be clear, very much a luxury item, not a necessity in any way. They've just become quite common over here.

The filters are also particulate filters; they won't do much if your water is actually considered unhealthy due to bacterial contamination/you're on a boil water notice.