The said Board of Water Commissioners shall adopt rules and regulations and a proper system of bookkeeping for the keeping of accurate accounts of the receipts and income received by it for water or from any other source from or for said system of water works and it shall show the rents and charges paid by every person, the kind and extent of service rendered him or her and when and where, and how much rent there may be overdue, if any. Said accounts shall also show all the sums expended and the purpose for which the sums are expended and said accounts shall, at all times, be kept separate from all accounts of said Village, and shall be public accounts and shall be open to public inspection.