Actually, some iodine, some handkerchiefs, and some leadership might have gone a long way to keeping a lot of people more hydrated than they have been. It's not healthy water but as long as you don't cube the problem with E. Coli poisoning it's probably better than dying of thirst. (See Slate.) It would have been difficult for the City of New Orleans to efficiently buy up its own stocks of Potable Aqua tablets and the like, but not so hard for FEMA to send a crate of the stuff (one iodine bottle should last a person for at least two weeks in my experience) to the Superdome last week.
I'm not so sure this would have been adequate. Portable purification technology is fine for biogical threats, but my understanding is that NO has a sizable chemical industry. You need special equipment to take care of that.
Anyway, related: this is kind of a cool idea.
That's cool, but the page notes that it doesn't stop giardia, which is bad. I think the pack is effective even against chemicals; see this and also answer 17 on that page.
The lifestraw rocks and is potentially cheap; hopefully everyone will eventually carry one with them along with their whistle and swiss army knife. (Yeah, I know, I'm being totally unrealistic. But go out and get yours people!)
Yes, I am, ahem, aware that iodine does not stop giardia. (cringes.) Giardia sucks. But it takes a couple days to go.
Re: the chemical soup--yeah, that would be a problem in the long run. But for the problem of staying hydrated, it's better to risk a little rise in carcinogen content.
Like I said, not perfect, but it would have helped some people stay hydrated a little longer. They could have at least spaced out their stocks of bottled water.