One of the things that I like about South America is that you have a choice when you buy water of having it carbonated (with gas) or plain (without). Of course, when purchasing water you need to specify which way you want it.
Here in Peru it is not quite as simple as asking for just that however. To purchase a simple water there are various things that need to be specified. The size of the bottle, the brand, and other things too. Many people offer water refrigerated or at room temperature too, so this also needs to be accounted for.
In the end, buying a simple water becomes a request something like:
Can I have a water, without gas, in a small plastic bottle, not refrigerated, of the San Mateo brand.
That is a lot of talking, or a lot of questions, just for one water. Choices are good but this is becoming silly.