All sums owed to the city for water shall be due and payable on the first day of the
calendar month following the calendar month in which the water is used or service
is available, and, unless paid by the 15th day of the month in which such sums are
due, the persons, firms, and corporations owing said sums shall be charged a penalty
of ten percent of the sums so owed or $0.25 cents, whichever is greater, for failure
to pay said sums within the required time.
