I first minimize trash by removing packaging before leaving the house. For the trash I do generate I use a garbage bag and store it inside the pelican that I use for my dry goods. I find that the box empties out at about the same rate as I generate the trash so there has never been a problem stowing it. By keeping it in the pelican, mice, and other critters stay away. If I have a lot of trash, I put it in a dry bag and stow it on the roof. The rinse out with a hose, so even if the garbage bag leaks it is pretty easy to clean up.
As for wag bags... Fortunately in Washington we rarely need them, but on those rare occasions when we do I have a completely separate system.
I purchased a bunch of
OpSaks. These seal up so well that bears can't smell their contents. If a bear can't smell it, then neither can I. I put the wag bag in the OpSak, seal it, then insure that it doesn't accidentally come open by using a
Clip-n-Seal. The clip-n-seal just insures that nothing puts any pressure on the zip-lock like seal of the bag. The opsak w/ the wag bag in it, goes into a *special* pelican case that I use just for this purpose. I think an ammo can would work just as well, but I wanted an extra odor and liquid containment barrier between me and the stuff.
