well tbh you should have had a letter when you moved in saying that you are on a water meter ( iirc its a meter if you have a new property ) and therefore you need to set up a payment method.

BUT its also your responsibility to pay your water, you know its not free and they would more than likely use that argument if you try and challenge them.

It probably is 50-50 but your still gonna have to pay for all of the water imo.

Sarah