You bring in an empty bottle through security to get airside, fill whatever size bottle you have in the crewroom (airside) and make it last for 10-12 hours. You can buy water on board from the bar at hugely inflated prices providing they haven't run out, or drink not quite boiling water from the galley. Can you imagine the 9-5 office brigade having to put up with what we do. Arrive at office with packed lunch, then have a security guard search you, confiscate any liquid/yoghurt/smoothie. Once at your desk fill up a bottle of water, then remain sat down for a 12 hour shift with no breaks. If you want the loo, then put your hand up and wait till everyone is sat and a colleague stands at your door (may take 20 mins). If you don't have enough to drink and eat after security steal and eat your food, tough! No-one would put up with it. Health and safety, unions, workers up in arms. Put on an airline uniform and it becomes a normal day.