I have had the UA rent a cops take off me an empty water bottle while boarding the UA flight between Sydney and Melbourne.

I had flown IAH-DEN-SFO-SYD it had been checked by TSO twice (IAH and SFO), just completed a 14 hour flight. Been checked by Australian security in transit. Bottle was empty, but still they refused to let me take it onto the plane.

Esclated to rent-a-cop supervisor (who had really really bad breath) who said the same thing. I asked to speak to someone from United, but was told none were available. Just to get away from his breath, I gave up the bottle.