Water meters on Strata title.

My Dad is considering buying a villa/ duplex. The property is strata titled with no common areas and the buildings are separate. the is one water main at the front of the property which than splits into 2 for each of the units. The council have said that they only read 1 water meter for the place, which is on the property my Dad is looking at so my question is what stops my Dad getting excess water bills for the other property if the council will only read 1 meter even if there are 2 to each of the units. Not sure if this is a common occurrence as I haven't really come across it before. The property is in NSW.