Third world countries I'm familiar with use the big office-type bottles which are reusable and not as wasteful. https://i.stack.imgur.com/TfVHl.jpg

Usually they have water purifiers. From simple ceramic filters to fancy machines using reverse osmosis and UV treatment.

In Thailand for example, they have vending machines dispensing drinking water into your own bottle.

We have a lot of them in the US. The usual ones are water machines for the big jugs like at Walmart. However, the companies selling machines that make bags of ice are adding purified water to their machines, too. One can see many styles by typing these words into Google images: ice vending machine bagged list.

Including the specific words since I got more nonsense results doing this search than about any other this year. Terms are too overloaded.

I grew up in a developing country. We boiled all our tap water for drinking.

I suspect most developing areas without clean water supplies are simultaneously unable to afford buying bottled water. They're often drinking dirty water, which they may or may not treat.

Parts of the US have tap water you better not drink. I would imagine China is even worse.

Bottled water is cheap, they buy it in 5 gallon bottles. I've seen that in many countries.