That depends entirely on which marathon you're running. There should be a published athletes guide that outlines what is permissible, if you're still in doubt I would email the race director and ask. A narrow interpretation would probably place that somewhere between "outside assistance" and "littering" both of which are probably not permitted. The general sentiment for amateur runners seems to be that if you want something other than what is officially supported at aid stations you have to carry it on and off the course yourself. Elite and sub-elite runners are treated very differently in that regard.

More practically what if someone walks off with your bottle, or kicks it into the middle of the street before you get there? I wouldn't want to rely that as a major part of my race strategy.