You can say that there is no common proper word for that, as you can't force one to exist if it doesn't. You can then just state how's it referred to. Note that I'm asking for a word that people would normally use, not some obscure term. The answer is therefore pretty much straightforward, except, say if there's a dialect issue.
The Portuguese word (from Portugal, not Brazil) "garrafão" might just have no equivalent in English. The word "demijohn" certainly must not be it, since an image search for that word reveals far different results from the object in question and shows how all the dictionaries that translate it as such may be wrong in that sense. "Carboy" doesn't seem to fit either. These are just common water bottles from the supermarket, typically of 5 liters.