Does the PNW mean the post-nuclear world? I can only guess how that'd be.
But I imagine they work just fine if filled with vegetation and even urine; or where there is only unpalatable water like on a beach or salt marsh.
The only problem I am having with the plastic is that at 7' x 7' it doesn't fold up small enough to fit on my canteen kit. So I'll either rig a way or it wil be somewhere else.