The funny thing is that I wear a 1.7 liter Camelbak when I go biking, but I never carry water when I run. I think I drank just over 5 liters yesterday and I just sucked down another liter after I ran just now, so I don't think I need to worry about dehydration. I need to get myself a water bottle to run with (with a strap) because I don't think it would be fun to run with my Camelbak, it just seems that they are way overpriced. I've been looking at something like
this because I don't want to wear a belt.
That's a good point you made about carrying extra in case someone else needs it.