Every single cell in your body contains water. Drinking plenty of water will help your cells function, which will help speed recovery. Your body will need more water than normal when healing. It is hard to understate the importance of staying hydrated.
Do not drink just when you feel thirsty; by that time, you are already partially dehydrated. Drink enough that you have to urinate multiple times per day, and so that your urine is pale yellow or clear. Dark yellow urine can be a sign of dehydration. Being a little bit hungry can be a sign that you need to drink as well.