Just my two cents. If you are dealing with 50-60 kids, I guess you would have to limit water. I live in Houston, teach in Katy, a western suburb, and it's hot here most of the year. I let kids drink till they are full. Yeah it takes a little longer, but in the long run, I think it's worth it.
My rules are: You have to drink continuously, not drink, dawdle, drink dawdle, drink dawdle. If you are waiting you have to stand an arms length back. Nothing aggravates someone trying to drink than the next person pushing into them or breathing down their neck.
I take my second graders to drink/bathroom 4 times a day. Yeah it eats up time, but I rarely/never have kids asking to get a drink, use restroom during teaching times.
But pe has to be really different.
Like this method for letting the kids take charge of the process.