I read through (thru?) the best cycling tips ever page and found a lot of contradicting opinions on the cold/cool/tepid/Luke-warm water issue...
If the water is cold it is better. This is from a physics and a Bio-Medical standpoint.
(I know it looks long but read on, it is worth it...)
U sweat because cellular respiration causes your muscles to heat up. This sweat causes you to loose water and electrolytes (both very important.) If you drink cold water then it will get absorbed into your blood *cold*. This cools down your blood which in turn cools down the rest of your muscles. You will heat the water up slightly as you absorb it but, the energy used to heat it up is energy that you cannot use to pedal, as it is the left over heat energy from respiration. This is just excess energy that you don’t need (hence the sweating.) An other cooling tip is getting your kidney areas wet (typically where your numbers are.) Your kidneys filter all of your blood, so cooling them down will cool you down.
It is official, cold water is better.
And an other point, getting your face wet and leaning forward will trigger your diving reflex. (This is what makes babies hold their breath). When your face gets wet and you lean forward your mind/brain thinks that you are underwater. Because of this your brain will stop producing saliva and stop sending blood to unwanted parts of your body, like your stomach. This isn’t a good thing to do before a massive 100+ mile race, rather something to do about 1k before the finish. It’s one of those little things that can help you out on the last stretch.
Finished....😄