Water in a commmunity evacuation comes down to 2 uses; consumption and basic hygiene. Guess what gets sacrificed? Water is heavy and bulky. There are no shortcuts. Carry what you can, and mirror the kit levels; small foil envelopes in a pocket, a personal canteen and larger containers. I was evacuating horses from a major ( arson set ) fire in Northern L.A. county today. Our truck trailer held personal canteens, my 21/2 gallon G.I. unit, 25 gallons in a saddlerack/ water carrier and 5 gallons in a Brit surplus water can. We encountered a ground crew that had exausted their personal canteens hours before. My brit unit is still up there with them.A good idea is to check with FEMA and other agencies. Find out what resources are available for the hazards of your locale.