Heat myth number 1: cold water only makes you warmer
It's true: when you drink cold water, you get warmer at first because your body wants to compensate for this.
BUT: The effect is minimal and short-lived. When drinking very cold water, the body can counter-regulate minimally - overall, however, the temperature is not as important as the quantity. The important thing is to drink a lot!
Whether cold, lukewarm or warm - the main thing is to drink regularly and enough. 3 liters on hot days is recommended.