I want to encourage all pre-senior and senior swimmers to carry a water bottle to practice. The pool water is warmer - 85 degrees; while during the winter it is typically 80 degrees. Swimmers do perspire during training and warmer water will only make it worse. Both groups are swimming more than a two hours a day so their perspiration / dehydration will be greater than the Rookie and Junior groups.

Studies have show slight under-hydration of 2-3% can adversely affect endurance by as much 10% and strength by 2%. (J. Novak, PEAK Symmetry Performance Strategies)

It is recommended athletes should drink water

1) prior to practice - drink 8 to 12 ounces of water 20 minutes prior. 

2) during practice - drink 5 ounces every 20 minutes

3) after practice - drink 16 ounces for every pound lost during practice

So I encourage each swimming to have a water bottle on the deck by their lane. I have most sets designed to last 15 minutes so after each set they should drink 4 to 5 ounces. 

Coach John