According to a report on NPR, "in a major disaster the government can spend $10-15 per gallon of water." (Link leads to a summary and an audio; LexisNexis has the transcript.)

Couldn't much of this water could be delivered at a fraction of this cost if price gougers were given free rein? Of course, the NPR report is hawking a gee-whiz technical fix, administered by FEMA, not a sensible market response.