Have you been overcharged for your water?
Unless your water is metered it is difficult to tell whether the supplier has definitely overcharged you or not. However, suppliers have been reprimanded in the past for billing customers up to 10 times what they should have been paying.
Customers do receive refunds if they've been paying too much for their water. So if your bill seems unusually high then it is well worth contacting your supplier about it.
How to make your utility overcharging complaint