im not sure abt QLD, but they would have to give you the proper notice of any intent of change to you're lease, if its not already stated.

if you're water meter is only to you're property you as the tenant have to pay the water usage/ landlord pays the sewage costs. thats just the law, it doesnt have to be in you're lease. so you would have to pay for the useage you have used, even past.

maybe give you're water supplier a call aswell.

if you're property manager is anything like mine, lazy lol