[A Navy Vet]

Mountain House freeze dried goods. Lasts 20 to 30 years. Just need water. Remember, your hot water heater has 50 gallons of drinkable water. Just attach a hose to the bottom drain. If you want to heat the water and live in a sunshine state try Sun Oven... there are others.

I have a Sun Oven and has easy set up with a self leveling pot and handles and temperature gauge. Once open, need to adjust the angle according to the Sun angle. It can actually cook food rather just warm and can pasteurize water or even sterilize instruments.

[LilFarmer]

A dehumidifier can draw 5 gallons a day of water from the air as well, assuming there is electricity