For bug-in water containers, maybe people can use plastic wastebaskets if better containers aren't available. For bug-out, Ziploc bags work and aren't as fragile as you might guess, though you do have to be a bit careful with them. The kind with the sliding plastic thing across the top does leak a little in the corner (not enough to make them unusable). The older pinch-together type are a little harder to operate but are quite leakproof in my testing.