I'm planning for a few Grand Canyon trips where the main problems are squirrels, mice, and ravens. The recommended system is Opsak bags inside wire mesh bags. I'm not sure how important the odor part of the equation is: the ground critters probably just explore everything in the area but there must be a reason that odor protection is recommended. I'll be camping at-large off-corridor. Since I'm not planning on cooking I'm thinking seriously about using soda or even water bottles instead of Opsak bags inside a wire mesh bag.

I did an experiment in the back yard, where we have a lot of squirrels and other small and medium animals active. I placed five small piles of shelled peanuts in a wooded, fenced section of the yard next to a creek that the dog can't get to. One pile was just poured on the ground. One was in a thin produce bag tied with a loose NOLS-cookery-style slip knot. One was in a normal Ziplock sandwich bag. One was in a flimsy disposable water bottle. The last was in a PET bottle that once held club soda. I placed a log partly over the bags and bottles just to keep them from blowing away, but not so much that a small animal couldn't bat them around. I also took a picture so that any disturbance would be evident.

Not surprisingly, the first two piles were gone the next morning. The Ziplock fell on the second night. After one week, the two plastic bottles are holding up, and are showing no sign of interest by any of the local creatures. Maybe I should try something stinkier.

Can anyone think of any reason, other than compressibility, why bottles wouldn't work as well or better than Opsaks for granular or powdered foods? Has anyone here done a controlled test of Opsaks?