Translation:The water is on top of the refrigerator.
Unfortunately "on" is a simplistic translation for 上. In English we use "on" for things "on top of something" but also for "on" the front or sides and even things that are under something: "there's gum on the bottom of my shoe". It's better to think of "上" as "on top". Your description would probably be: 冰箱的外面有水.
Chinese at least in the mainland don't like to drink cold water. So I assume it's a small fridge also used as a bench/shelf/table and there's a bottle or jug or even the electric kettle sitting on top of it.
Either that or it's a mistranslation but in that case they mistranslated both the Chinese and the English so it doesn't seem likely.
Sure it is. It's perfectly acceptable. If 'the water is on top of the cupboard' is acceptable so is 'on top of the table'.
George has just discovered an inconsistency. (I say just...).
It should accept both...
The water is on the fridge and The water is on top of the fridge.
In this context the sentences are equivalent.