You don't need to drink plain water to stay well-hydrated as most other beverages will do the job.

We're often told to make sure to drink about eight 8-ounce glasses of water every day to keep hydrated and healthy. But the water content of food, and beverages other than water can hydrate the body equally well, say researchers at the Center for Human Nutrition at the University of Nebraska.

A group of 27 healthy male volunteers was put on one of two diets. Either they got their fluids from plain water, or from other beverages like orange juice, cola drinks or coffee. Urine analysis and body weight measurements revealed no significant differences between the two groups. This suggests that if it's difficult to get access to plain water every day, you can still fulfil your hydration and health needs by drinking other beverages.

Source

Journal of the American College of Nutrition 1st April 2003