Abstract: A water system that allows a bicyclist to drink liquids anytime he desires. The system has a collapsible container of water or other liquid stored within a flexible back pack that is removably secured at a location between the shoulders of the bicyclist. A resilient mouthpiece adapted to be held in the mouth of the bicyclist is connected to the container by a length of tubing. The mouthpiece is a valve device and has a cylindrical sidewall that forms a chamber. A spring biased valve element located inside the chamber normally prevents flow therethrough. When the opposed sidewalls of the chamber are compressed between the teeth, liquid flows through the mouthpiece. This allows the mouthpiece to be held securely between the lips and whenever the sidewalls are compressed by the teeth, fluid flows from the container, through the tubing and into the mouth of the bicyclist.