This isn't a ban by Qatar Airways. They are highly opposed to the ban. And on the water ban enforced at the airport (and sometimes the gate), Qatar Airways doesn't charge for beverages (including alcohol), they'll happily give you litres of bottled water for free (although for some reason odd reason they cut the label off when you ask for a 2l bottle - and no its not tank stored potable water - i get thirsty during long flights - tis just easier this way).