Once you sign into your account’s history settings, you are just a couple of clicks away from some peace of mind.
Image courtesy of Electronic Frontier Foundation.
From the blog post: Note that disabling Web History in your Google account will not prevent Google from gathering and storing this information and using it for internal purposes. It also does not change the fact that any information gathered and stored by Google could be sought by law enforcement.
With Web History enabled, Google will keep these records indefinitely; with it disabled, they will be partially anonymized after 18 months, and certain kinds of uses, including sending you customized search results, will be prevented.
The post also provides a link to the EFF’s Six Tips to Protect Your Search Privacy white paper if you would like to do more to reduce the records kept on you at Google (see last paragraph of blog post).