Unfortunately, the FAA came down on us for not being thorough in collecting all service items provided to guests during the flight, so we are now instructed to collect everything prior to landing, including water bottles. This is simply because if something that we provided were to act as a projectile during a hard landing, we would be held responsible for it. I know it seems petty (I have never seen so many people reluctant to hand us the water bottles - like it's the last beverage they'll receive in their lives lol), but we have to follow all FAA directives, as they appear on flights and observe everything we do.