HELP! My father just received a $7,100 Water Bill

HELP! My father just received a $7,100 Water Bill

My father is a small single apartment owner whom just received a $7,100 water bill for the month of October and November 2022 . He tried to call the water dept to dispute this but they only want to start him on a scheduled adjustment payments.

Is there anything or anyone I should hire to help my father fight this ridiculous water bill?