About 7,500 Columbia water customers were mistakenly charged an extra $6 on their August bills.
Angela Adams, customer service administrator, said the affected customers – 6 percent of the city’s residential customers – will receive a credit on their September bills.
Adams attributed the mistake to a new rate structure and a different format for monthly bills. The mistake only appeared on some August bills of Columbia residents, she said.
The mistake was brought to her attention Monday by a customer. Late Tuesday, the city’s information technology department was trying to determine how many people were affected.