The search giant keeps information from each search made using its engine, including the search terms, the IP address the search came from, and details such as the web browser used.
Its policy is now to make this data anonymous after 18 months rather than the 18 to 24 month term it previously held to.
The change resulted from concerns raised by Article 29 Working Party, a group of data protection commissioners from the European Union, in a letter to Google. They claimed that Google seemed to be failing to respect EU privacy rules.
Google's global privacy counsel Peter Fleischer has written back to the group to notify it of the change.
Fleischer wrote: "After considering the working party's concerns, we are announcing a new policy: to anonymise our search server logs after 18 months, rather than the previously-established period of 18 to 24 months."
Fleischer added that the company would "firmly reject" a retention period that was any shorter.