Just because you drink over 1 gallon a day now does not mean you will not survive on less for a very long period of time

I think the reason not many suggest 5 gallons per-person per-day is they don't want to overwhelm people and make them think it's not possible to be prepared.

Personally I live near a Lake and multiple rivers (within 5 minute walk) so water is my LEAST concern. I do however get 5gallon jugs delivered weekly so I've always got atleast 15 or 20 gallons on hand.