Holidaymakers heading abroad this summer should be aware of airport security rules that could cause delays at checkpoints. Although many UK airports have scrapped the 100ml liquid rule thanks to advanced scanners, one exception remains for stainless steel bottles.
Stainless Steel Bottles: A Security Exception
Metal water bottles are permitted through security, but they must be completely empty. The new scanners cannot penetrate the double-layer insulation of stainless steel bottles and thermos flasks, requiring them to pass through empty for safety reasons.
Fortunately, most airports provide free water refill stations after security, allowing travellers to fill their bottles once through the scanners.
Major Airports Relax Liquid Rules
Major airports including Heathrow, Gatwick, and Birmingham have introduced relaxed liquid rules as of May 2026. However, Edinburgh Airport warns passengers: "If you are carrying metallic or double-walled containers (including vacuum flasks, thermos flasks and metallic water bottles), please ensure the container is empty prior to the security checkpoint."
Playing Cards Also Cause Delays
It is not just water bottles that trigger delays. Playing cards can cause additional screening because their stacked shape and density may suggest something hidden inside. TSA expert Ian Cava advises passengers to remove cards from hand luggage and place them separately in a tray to speed up the process and reduce delays.
