Soon, a new crop of senators will make their way to Washington to help run America. Some may even want to brighten up their Senate desks with a nice vase of flowers. Except that’s not allowed. And if they want to quench their thirst, they'll find their beverage options severely limited by a decades-old precedent. It’s just part of the many peculiarities of life in the U.S. Senate. Here's the history behind five rules every senator needs to follow. 1. Senators can only drink water or milk on the Senate floor. Vice President Spiro Agnew (left), Senator Dirksen (middle), and President Richard Nixon (right).National Archives and Records Administration, Wikimedia Commons / Public Domain