Running a Marathon in 3.07 without drinking any water...how much faster could this person have gone?

No way to tell without knowing how much he sweats. I think I read in Daniels' running formula about 2 people where one sweat 3x as much as the other.

Sounds like he would have run slower.

Well, if if water messes up his stomach, than I'd say he'd run about 4 minutes slower if he drank water.

What do you think I could run if I slept more than 8 hours a night? What do you think I could run if I never got legs cramps? What do you think I could have run if I were born faster?

You do know Boston did not have water stations until the early/ mid 80's and BR (and others) ran like 2:09 scarfing what they could from the crowd? I bet there were a lot of dry sub-3 hour efforts back in the day.

Don't know if I'm the only one...I could not coordinate drinking and running until after about 10 marathons. I would end up snorting in some or choking/coughing and have to stop for 10s. So my first 10 or so marathons I never drank. Always ran 2:25-2:37. Learned to drink and no change in times!...I still run my long runs (app 20-30 mi) with no drinks but at 6am so its cool.