Am I missing something?

I understand that the people still stuck in New Orleans need food, shelter and the rudiments of civilization, such as an absence of armed predators roaming the new canals. But the one thing that’s confused me is how the networks keep talking about how the people don’t have any water. Is all that water covering the streets too briny to boil, perhaps? If it’s merely filthy, as I assume it is, isn’t the whole point of boiling water to purify it in the first place?

I have no point here, I was just curious.