An audit could call into question the accuracy of thousands of water and sewer bills in Atlanta, a newspaper review of city documents has found.

City officials are trying to determine how many residents may have been overcharged, The Atlanta Journal-Constitution reports (http://bit.ly/OSOXBn ). The newspaper got the preliminary audit results through an open records request.

The audit of more than 160,000 water meters found that about 90,000 needed repair. Only about 30 percent of the audited meters had no problems, the documents show.

“Where we have identified problems, we have been and will be proactive in rectifying them,” said Hans Utz, the city’s deputy chief operating officer. “We are committed to identifying what the issues were and how we can make it right.”

With some of the country’s highest rates to pay for $2 billion in sewer upgrades required by federal regulators, Atlanta residents have complained for years about readings they say are improbable. City officials say they are still gathering data, and thousands of meters have yet to be inspected. The audit is set to end Aug. 22.

People who were overbilled will see their accounts credited. If the audit finds inaccurate readings, Utz said residents won’t have to go through the city’s Water Sewer Appeals Board, which many residents have said is confusing, frustrating and arbitrary.

The audit came five years after the city started a $35 million project to install electronic meter reading throughout its water system. That project was supposed to improve the accuracy of bills, identify potential leaks and cut the time it takes to read individual meters.

Now Atlanta’s residential meters transmit radio signals showing how much water a property uses. Reports of problems, such as faulty readings from upside-down antennas, surfaced soon after the expensive changeover to automated meter reading.

“We were getting an awful lot of calls about billing problems,” Utz acknowledged. “That triggered this audit. We are fixing things as we go.”

The 11-month audit by outside contractors Arcadis/BPA and JP2 began on Sept. 19. The $2.4 million cost does not include the expense to repair or replace meters or lids. As of Wednesday, 77,415 meters had been repaired, with another 12,941 repairs scheduled.

Some 6,000 meters couldn’t be reached because of trees, sidewalks, landscaping or other obstructions. Those may have to be removed so the meters can be checked. Atlanta officials have not yet determined the best way to get access to some of the meters.

“If we put a sidewalk over the meter, then that’s our responsibility as a city,” Utz said. “But if the homeowner planted a tree on the meter, we’ll need to work with the homeowner to figure out the best way to access it.”