Polar bears rarely drink fresh water, as they derive most of their water needs from the chemical reaction produced when fat is metabolized. This is the main reason why a polar bear's diet is extremely heavy in fat provided by animals such as seals.
Polar bears are also well adapted to conserve as much water in their body as possible. This is largely due to their kidneys, which are specially designed to remove salt from blood plasma in addition to concentrating the urine. Polar bears also do not consume a lot of protein, so the kidneys are less taxed by waste when compared to most other carnivores.