If there is one thing that is worse than disposable bags, it is disposable bottles.  The amount of energy and water that is necessary to deliver water to you in a disposable bottle is astonishing.  The most astonishing thing about it is that people still regularly spend money for water in bottles when the water from the tap is held to such high standards, and sometimes bottled water is really just tap water.  Search for reusable water bottles.  Fill them, and yourself, up with watery goodness.  Resuable water bottles are just another way that you can choose the environment over convenience.