The monthly sewer use charge is calculated based on an average of monthly water usage by the customer for the months of December, January and February. The average is calculated and effective with the utility billings beginning the following March 15. The winter months are used to set an average in order to avoid the summer high usage months in fairness to the customer. A new average is determined annually. For new accounts the average of monthly water usage is set at 3,000 gallons until an average can be determined based on the designated winter months. Prior to a new average being set, the default average of 3,000 gallons may be reviewed for consideration of adjustment upon request of the customer after 3 full months of usage.