Good point Chu-Chu. Looked it up, the 2-liter soda bottles are good to 50 psi.
Cabin differential pressure at 35k ft is 9 psi. Can't be as confident as before, but those clear water bottles in the photo are more flimsy than the 2-litter ones. Might do a little experiment in the hangar later.
Another aspect of the water bottles is that many flight attendants intentionally don't tighten the caps when they are empty. If you do, you get an uncomfortable crackling sound as the cabin descends and bottles collapse.
Not sure you can tell much either way from the condition of those bottles. They may have been emptied at altitude, had tightened caps, partially collapsed at sea level and popped back when opened after recovery.