Brisbane Australia mate, and yes, they have water cops, and if you are caught impounding water on your property without a permit, the water will be confiscated, you will be fined, and you will be put on a list to be physically checked on a regular basis. No busting down of doors in the wee hours, but they are effective at what they do nonetheless. They are just like the code enforcement officers hired by planning departments here that go around and look on people's properties to see if they have anything they shouldn't, like an shed in an easement, or a carport attached to the side of a house, etc.

You get charged for whatever water you collect just as if it came out of the tap. There was a joke going round that next we'd be getting charged for breathing air as well.

I wouldn't laugh too loud about that one, mate.