A British watchdog has given Google 35 days to delete any remaining data collected while taking pictures for its street view service or face criminal proceedings.
The UK Information Commissioner's Office reopened its investigation into Google last year after further revelations about the data taken from wi-fi networks.
During that inquiry, additional discs containing private data were found, the BBC reports.
Google had previously pledged to destroy all data it had collected, but admitted last year that it had "accidentally" retained the additional discs.
The ICO has told the search giant to delete the information and said it must inform the Office if any further discs of information are discovered, but did not impose a fine.
It concluded that the collection of the data in 2010 was due to procedural failings and a serious lack of management oversight, but agreed with Google's assertion that the company did not order the actions at a corporate level.
In a statement on Friday, Google said said it works hard to get privacy right, and quickly tightened systems to address the issue.
The internet giant said it was proceeding with its plan to delete the data.