Average is to work out 60 - 90 min a day? How many days a week? Cardio, HIIT or lifting? All will make a slight difference. Water is probably the healthiest option but remember everything counts(even food) towards the 2.7/3.7L recommendation. Have you tried eating pizza and working out again to see if you get the same results?
Bottom of the page mentions that some are fine drinking less than 1.9L (
https://www.mayoclinic.org/healthy-l...r/art-20044256)