Is thirst a goods indication of the need to drink more fluids?

Not necessarily. Thirst can be slow in developing when more water is needed quickly, for example in hot weather with heavy exercise. Also many people are not aware of thirst signals or confuse thirst signals with hunger signals or don't get around to drinking more water when they notice early signals. Awareness of early thirst signals tends to diminish if those signals are not habitually acted on.

Thirst is a satisfactory indication of the need to drink when:

• the body's need for water develops gradually over time.
• the individual notices early thirst signals, and
• action is taken to drink more water