[GordonS]

I don't know about "most countries" - at least, I believe it's OK to drink tap water in most of Europe and Scandinavia.

[tomatocracy]

Yes, it’s pretty common in much of the developed world.

But if you think about it, it’s a pretty big waste of resources to use water purified to the point of being safe to drink for showering, filling toilets, watering the garden, washing the car, etc. The vast majority of the water you use doesn’t need to be drinkable.

[ahartmetz]

Only one system of pipes and AFAIK there is nothing particularly labor or energy intensive about producing potable water (in temperate climates).

[seanmcdirmid]

According to https://i.redd.it/q428xlnjh2f21.png, only much of Europe (EU mostly), not most (by population or area if Russia is considered).