Not an explanation. People buy bottled water before the disaster, while they still have safe tap water. They could have filled containers at their home with the safe tap water that they still had.
That would work for tap water you’d stored, but not for potentially contaminated tap water or surface water. I have various water filters and purifiers for camping, but they deal with bacteria and viruses, not, for example, toxic chemicals or heavy metals. If you’re worried that your tap water is contaminated by spills from a compromised hazardous waste site, camping water filters will not solve your problem.
Agree, @“Cardinal Fang”. It would be to treat stored, stale tap water.
In general, I don’t drink bottled water. But we are near the coast and buy if there is a potential hurricane coming. Convenience, logistics, etc. We have filled up a bathtub but as someone said, that would be to flush toilets. We lost power for 6 days during Isabel. When I see these recent events, I feel lucky that it was not worse. Sad to see the devastation in Texas. These events seem to be increasing and that is scary. Between floods (coastal and riverine), earthquakes, wildfires, and tornadoes, most of us are vulnerable.
That mainly applies in areas after a disaster, water contamination outbreak, or areas with abysmal water management(Flint, Michigan).
Another thing to keep in mind is that tap water is regulated more stringently by Federal regulations than bottled water and some bottled water brands(i.e. Niagra) have been recalled due to e-coli and other contamination.
Only times I use bottled water is if I am going into an area where there’s no source of food/water for miles for 4+ hours on a hot summer day. Otherwise, I’d wait until I find a restaurant/grocery store/supermarket or get back to my apartment.
I don’t understand needing small bottles instead of gallon containers- pour it into a glass, duh. So much plastic waste generated (we know so many will not recycle).
Actually. You can buy the multi gallon containers, like in office water dispensers.
The camping filters are aldo often marked not for sustained use.
I’m adding this link, no idea who she is but it notes making the right donations. https://angeliagriffin.■■■■■■■■■■■■■/2017/08/31/the-wrong-donations-some-tough-words-on-disaster-relief/
And it’s not just plastic that’s the issue. The manufacture and transpo of all those bottles meanstrucks on the road, their pollution.
Actually, you can buy the multi gallon containers, the sort used in office water dispensers. And it’s not just the plastic in small bottles that’s the issue. The manufacture and transpo of all those bottles uses energy resources and can spew pollutants, too.
The camping filters are also often marked not for sustained use.
If you’re sending goods to Texas, just check they’re what’s needed. Saw a comment today about the number of, eg, winter coats they’ve received. Good intentions, wrong destination.
Maybe those winter coats came with an implied suggestion that people move north. 
Honestly, cash is what is needed and better than sending your used stuff. 
"But Bob Ottenhoff, president and CEO of the Center for Disaster Philanthropy, has some words of caution for those who want to help.
“This is not the time to be donating products or even services,” he says. “That’s frequently the urge, and most often that is the wrong thing to do. …With the floods blocking off streets, when warehouses are not available, there’s no place for these products — there’s no place to store anything, there’s no place to distribute anything. And that’s going to be the case for some time.”
Instead, he says, people should give money to groups they trust, and that have the ability to provide aid where it’s needed most."
"Derrick Chubbs, president and CEO of the Central Texas Food Bank in Austin, agrees that cash donations are best for groups like his, which is trying to help with emergency food distributions. The Houston food bank — the largest in the country — has been shut down by flooding, so others in the state food bank network are pitching in.
“I say donate funds, because we can use those to purchase exactly the type of disaster relief supplies that are going to be most helpful,” Chubbs says. “It also avoids complications of sorting and having to distribute varied types of food items.”"
Move north? Good luck with escaping hurricanes by doing that. Anybody remember Sandy?
Move to Minnesota. 
Or pretty much anywhere in the Midwest. The idea that some people have that all areas of the country are equally susceptible to natural disasters is amazing to me.
Of course, different areas of the country are more prone to different kinds of events. Flooding in Minnesota , areas in the Midwest , would result from river flooding, not hurricanes.
Any area of the country could experience droughts, floods, wildfires. Some areas are more prone to snowstorms, earthquakes (not just CA), or tornadoes. There is no shangri la here. As far as telling people to move to the midwest, be careful what you wish for.
Midwest - tornadoes and cold.
How do you move multigallon water containers? Water gets heavy fast.
I agree with cash donations. Stuff takes so much labor to distribute that I don’t think it’s appropriate for an emergency.
Add snow!
Snow, ice and cold don’t work for me, nor do snakes. I need temperate climates, like HI, but we have to deal with volcanic fog and tsunamis and some hurricanes as well. There seems NO ideal place that has NO danger or fires, floods, other weather disasters AND has good jobs, inexpensive cost of living and all the things most of us want.
Tornados damage one or two streets. Many times just a few houses. Not anything approaching what you see with hurricanes, wildfires, etc.
And again, the idea isn’t that any area couldn’t experience certain types of natural disasters. Just that certain areas are much more prone to them.
In terms of the cold, that is what the winter coats are for, remember?
Well, I doubt that winter coats are on the top 10 list of what the people in Texas want or need right now.