How long are you guys playing for? Maybe if I was playing all day I would be concerned about it. But otherwise I never even think about it. However I carry a one liter aluminum water bottle everywhere I go in the summer.
I highly recommend NOT reusing plastic bottles or using nalgene type bottles at all. That plastic is bad stuff, its proven.
oh, sorry my incidents happened when I was doing long distance running for a grade or while representing my company.