In short- yes! Most of us are not drinking enough water which leaves us feeling tired, unable to focus, irritable, and sometimes hungry. The average adult needs 8 glasses of fluid each day- this includes all of your cups of tea too.
In the summer and when you exercise you will need more water to account for fluid losses. We also consume water through some foods such as fruit and non- starchy vegetables.
If you are a person who struggles with an afternoon slump or who arrives home from work starving or craving an alcoholic beverage- have a big drink of water and see if this is what you are really craving.