Yes - I'm talking a long term emergency, BUT ... even being trapped in your car during a blizzard or a break-down in a rural area, water is priceless. I recommend you keep a case of water in each vehicle. No area of America is immune to disasters.
Here's what your Mother, your brother, your best friends and everyone else should know:
Rule of 3s - You have as little as:
Am I making my point? We have to use all of those factors for our survival kit.
3 Minutes to solve lack of air, a serious wound or shelter in sever weather
3 Hours without Shelter if weather is moderately sever
3 Days without water (but your body and reasoning suffer greatly - stay hydrated daily)
3 Weeks without Food (the more smart calories the better during the aftermath - you'll need your strength)
Follow my concepts and find your favorite or your favorite variations to this One Day Bag:
I will demonstrate this with my smallest Camelbak, but you can use any fanny pouch system even with bottles also. I prefer two water containers for balance, OR one full and the other is an empty, filter system, so I can quickly drink 'any' water.
I picked my tiniest Camelbak for this Instructable to show What-is-Possible with limited space and money. Imagine what just a little more space and resources might give you.