For the sake of my dog, all year around I have long had a bit more than a gallon of water in the car (a Honda Element) -- in 48 oz and 32 oz Nalgene bottles and canteens. I keep those in a Coleman steel cooler, in case of leakage. I periodically switch out the water for fresh and before winter will begin leaving 3" or so of air at the top to accommodate freeze expansion.

My Samoyed, Gidget, recently died (at age 14 years, 2 months) and I'm currently dogless but will continue carrying water.

Food-wise, it's too hot half the year to keep any in the car but during winter I'll have some breakfast bars in there -- which I will eat and replace as needed. I do a lot of winter hiking and biking so like having a quick snack handy.

If I were going on a long roadtrip I'd have more.


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