London’s Heathrow Airport (LHR) has officially completed the full rollout of next-generation CT security scanners across all its terminals, allowing departing passengers to carry liquids in containers of up to two litres without removing them from their bags during security screening. The upgrade also means electronics such as laptops and tablets can remain inside hand luggage, and the long-standing requirement to use clear plastic bags for liquids has been lifted for outbound flights from the airport.
With the completion of the project, Heathrow now claims the distinction of being the largest airport in the world to fully implement the new high-tech screening equipment. The scanners generate more detailed, three-dimensional images of cabin baggage, enabling security staff to assess potential threats more effectively while streamlining the passenger experience.
While Heathrow is the biggest airport to complete the transition, it is not the first in the United Kingdom to introduce the technology. Gatwick (LGW), Edinburgh (EDI), and Birmingham (BHX) airports have already deployed CT scanners and raised their liquid limits to two litres, while Bristol (BRS) and Belfast (BFS) airports have also increased their allowances. However, the picture across the UK remains mixed. At most airports, passengers are still permitted to keep liquid containers of up to 100ml in their bags without removing them, but larger quantities are not yet allowed unless the airport has explicit approval.
Several airports that have already installed CT scanners are still awaiting clearance from the Department for Transport to increase their liquid limits beyond 100ml. This has contributed to ongoing inconsistency in security rules nationwide, a situation that has frustrated both passengers and airport operators.
The rollout of the new scanners has faced repeated delays over the past several years. In 2019, then-Prime Minister Boris Johnson announced plans to scrap the 100ml liquid rule by the end of 2022, but the COVID-19 pandemic derailed that timeline. In December 2022, the government again pledged a major overhaul of airport security, setting a June 2024 deadline for the installation of advanced scanning equipment across UK airports. That target ultimately proved unrealistic for larger hubs with multiple security lanes, even as some smaller airports managed to meet it.
Confusion intensified in June 2024 when the government instructed airports that had already lifted the 100ml restriction to reinstate it temporarily, a move that drew criticism from the aviation sector. The European Union also reverted to the 100ml rule later that summer, further complicating messaging for travelers. As a result, passengers were advised to assume the stricter limit still applied, regardless of where they were flying from.
Heathrow’s scanner program forms part of a broader £1 billion investment aimed at modernizing the airport’s infrastructure. Airport officials say the new equipment can process thousands of passengers per hour with greater efficiency while maintaining rigorous safety standards. However, consumer group Which? has reported that the increased sensitivity of CT scanners at some airports has led to more manual bag searches, potentially offsetting some of the time-saving benefits.
Importantly, the relaxed liquid rules currently apply only to flights departing from Heathrow. Passengers are still advised to check security requirements at their return airports, as restrictions may differ. Among the world’s ten busiest airports, Heathrow is currently the only one to have removed the 100ml limit for liquid containers on international departures.
Industry groups have warned that airports setting different timelines for lifting the restriction has led to confusion and frustration for travelers, underscoring the need for clearer, more consistent communication across the aviation sector.