Walters swam the first leg of the 4×200meter freestyle relay preliminaries (in 1:46.57) with Ricky Berens, Erik Vendt, and Klete Keller. Their time of 7:04.66 broke the previous Olympic record of 7:07.05 set by Australia in 2000. In the final of the 4×200-meter freestyle relay, Michael Phelps, Ryan Lochte, Berens and Peter Vanderkaay swam a combined time of 6:58.56, a new world record.