All bills for water and sewer are due and payable on the first day of the month following the month in which they are issued, and shall be delinquent at the close of office hours of the tenth day of the month in which such payments fall due; provided, that if such tenth day of the month falls on a Saturday, Sunday, or legal holiday, then such bills shall be delinquent at the close of office hours on the next succeeding business day. If not paid before delinquency, a penalty of ten percent (10%) of the amount so due shall be added to said amount due. (Ord. 735, 11-17-1999)