Being dehydrated can lead to a multitude of issues for your body, including your eyes!
Every organ in the body needs water to function properly, including your eyes. When the body isn’t properly hydrated it tries to conserve what fluid it does have by, among other things, decreasing fluid output. This could include decreasing tear production. This decrease in tear production can lead to mild symptoms of dry eye. If you are experiencing dry eye it will not be immediately evident to you if your symptoms are related to hydration so as a general rule of thumb it’s best just to continuously maintain proper levels of hydration by regularly drinking water.