True. The body is perfectly capable of telling you when it needs water, it's called being thirsty. If you're thirsty, drink, otherwise don't.

sort of correct. As one ages the body starts doing a poor job of signaling thirst.

https://medlineplus.gov/ency/article/003086.htm

> As people age, they are less likely to notice their thirst. Therefore, they may not drink fluids when needed.