We decided not to get the extra bins and see how it went. As there are only 2 people in the house and 2 in the granny flat we didn’t need them. I think it was about $300py for the extra bins. Ask your council.
If you have separate water meters then you’ll have 2 water rate usages.
We live in the house so we included water and electricity in the rent.
You can have them separately metered though. Or you could just pay the usage yourself. It’s only part of the bill and you can only claim it if you have the complying water taps etc. You can only charge usage if separately metered also.
If you had overflowing bins then you would need to get extra bins.