i ride about 100 miles a week, from wrigleyville to the loop and back, and to school and back...
So about 20 miles a trip. That's a little far to go without any water. Where do you keep your water?
Where do you keep your spare tires?
For me it is easier to keep that stuff on the bike. If I don't keep all that stuff on my bike I will forget it.
I don't really park my bike outside either. If I did that I would probably not leave the stuff on the bike.