I have a friend whose dad owns some property outside of the city, and best of all he's got a well -- limitless, unpaid access potable water. Assuming we can survive the crush to get out of the city, I think we'd be able to last a while out there; both of them are gunners, and so are my dad and sister.
The cool thing about SA is that we've got some of the gnarliest doctors on the planet here at BAMC, and there's also supposed to be a live-fire training facility for tanks somewhere north of town too, I was told. If all else fails, Fort Hood is only a couple hours north and they're the biggest base on the planet; barring "The Government did it" purging scenarios, or comical hollywood military impotence, I think we'd be able to make it until they came to save us.
If all else fails we've got enough ammo at my house to fight our way through every zombie in my neighborhood; my friends all unofficially agreed to come here in the event of the apocalypse. The friend whose dad owns the property already said he would find me, especially after we found out I could one-hand a 4" .500S&W with relative ease and accurately when he let me shoot his.