I did read that which is why I posted. As I see it, a place without water wouldn't be settled
Sometimes you don't have a choice, or the world changes around you, and you have to adapt.
and a location with a non-potable water source should be able to clean it themselves like medieval London.
Mentioning, but setting aside that...
1) Cholera and dysentery were common ailments in London at the time, so, maybe they didn't clean the water as much as you suggest.
2) Part of London's solution was miles of lead lined piping to carry water from the Tyburn. I'm sure that caused no trouble to anyone at all.
...you seem to miss the point - this
IS the game's version of "clean it themselves"! It is just using magic spells, since that's what the game actually gives you to work with.
At least on an earth like material plane. So to me you basically said the decanter is valuable where no one lives. If that makes sense.
Where no one lives?
I am sorry to have to correct your ignorance on this matter: today, right now, in the 21st century, about one-quarter of the planet's population - a couple of
billion people - live without safely managed, reliable drinking water. And about 700 million have effectively no access to safe drinking water at all.
War, drought, and economic depression can and do limit people's access to clean water, and have since the beginning of civilization! I don't know what planet you have been on, but this one isn't one where everyone actually has always had good water to drink, cook, and use for hygiene.