Retention of Records. The utility shall retain customer billing records for the length of time necessary to permit the utility to comply with Regulation .05, of this chapter, but not less than 3 years. Records For Demand Charge Customers. Records for customers whose billing includes a separate charge for a measured demand shall show: KWH meter reading; KWH consumption; KW meter reading; KW measured demand; KW billing demand; Net amount of the bill.