A normal person who sits at a desk all day and does next to nothing needs to drink 6-8 glasses of water (or equivalent) per day to remain well hydrated. So, if you are an active, young athlete, you probably need at least that much plus more to rehydrate after sweating / exercising, etc.
When you state that water has no nutritional value, you mean that it has no vitamins, proteins, or carbs. However, consider that your body is 60-65% water — so the “nutrients” are only applied to 35-40% of your body’s needs. In other words, your body needs water more than it needs nutrients.
While we’re on the subject of percentages, you should know that muscles contain 75% water; bones 22%, blood 83%, lungs 90%, and brain 70%.
The water in your blood helps digest food, transport waste, and control your body temperature.
So, knowing all these numbers, do you think water has some value, if not “nutritional” ?