If a person or business charges $15.00 for a case of water that normally sells for $3.99 inan area with an impending hurricane, is that price gouging?

I say that's gouging. If supply was in that much demand they would be hoarding it not selling it.

It's price gouging, and it's usually against the law to do it on essential products in/after an emergency.

I would say it's price gauging UNLESS there is a good reason for it like it's now hard to come by.

If it is their normal prices, then no, it is not. But if Sams or Costco charged that much for their own label water, then yes it is price gouging. Lots of water costs that much per case. Like Perrier.

Depends what they're charging that much for.

for what?

It could be considered so---unless more is involved in getting that water to customers than usual.