I often find that healthy portion sizes of fruit and vegetables won't provide us with all the fluid we need but they're a great source of "time-released" fluid. Unlike a glass of water, which leaves the stomach and gets into the blood stream relatively quickly, food takes longer to be digested and therefore releases water into your system more slowly.
Why is hydration important? Around 70% of our body is made up of water; it is vital for every chemical reaction in the body. We need around 2-3 litres a day to transport nutrients, help with cellular enzyme activity and digestion of food, to carry out waste and toxins and also to support brain function for mood, energy and concentration.