When your body is thirsty, it needs water. However, this principle does not apply to dry, thirsty skin. We tend to think that drinking a lot of water can cure dry skin, but the truth is that it’s not effective.
A normally-hydrated person probably won’t see a difference in their skin after drinking an increased volume of water. Drinking an excessive amount of water can lead to other health problems and is not recommended (nor effective) for dry skin.
Dry skin is an external problem and is best treated from the outside. External factors such as cleansing products, environment and oil glands determine how dry your skin is or will become.