If you’ve flown through London’s Heathrow Airport (LHR) in recent years, you may recall the frustrating experience of having to transfer your airplane-sized toiletries into a clear plastic bag, arguably slowing the already lengthy screening process down. But clearing the security line just became much smoother for the millions of passengers that pass through Heathrow each year, thanks to the completion of a £1 billion (about US$1.37 billion) upgrade to scanning technology that has enabled the hub to ditch previous carry-on limits for liquids.
Fliers can now keep liquids in two-liter containers (about half a gallon; more than five times than what was previously allowed) in their carry-on bags—which means you no longer have to toss that full bottle of water or corral travel-sized toiletries into a small plastic bag. Another perk of the new scanning technology: Passengers don’t have to remove laptops or other electronics like tablets from their bags and place them in separate bins.
The new rules apply to all four terminals at Heathrow, all of which are implementing the upgraded computed tomography (CT) scanners that provide better images of cabin baggage. The move also offers some sustainability benefits, as Heathrow expects it will eliminate the use of approximately 16 million plastic bags, since they’re no longer needed to hold carry-on liquids.
With the upgrade, Heathrow is now the largest airport in the world to fully roll out the next-generation CT security scanners, “a move that promises faster queues, less stress, and a smoother start to journeys for millions of travelers,” Heathrow airport authorities said in a recent statement.
Slow rollout of new scanning technology
The enhanced security technology now available at Heathrow helps eliminate a long-standing annoyance among many travelers: They had to limit their carry-on liquids to a 100-milliliter volume—about 3.4 ounces in U.S. measurements—and place them in a clear plastic bag that had to be removed, along with electronic items, from carry-on luggage at security screening checkpoints. The rule had been in place in the U.K. and in the U.S., since late 2006, following a failed transatlantic terrorist plot that relied on carry-on liquids.
In December 2022, the U.K.’s Department for Transport announced a new security policy shift that would have all U.K. airports scrap the 100-milliliter limit by 2024, thanks to the implementation of the upgraded scanners. However, the department later granted an extension for that rollout.
Fliers departing from London’s Heathrow Airport no longer have to limit their carry-on liquids to 100-milliliter bottles in a clear plastic bag.
Photo by Viktorya Telminova/Shutterstock
In 2023, London City Airport (LCY) became the first major U.K. airport to adopt the enhanced scanning technology and lift its 100-milliliter liquid limit, allowing laptops and liquids to remain in all passengers’ carry-on bags. But the rollout also has experienced several delays, and some U.K. airports, including London Stansted (STN), Luton (LTN), and Manchester (MAN), still have the limit in place—meaning passengers should always check restrictions before traveling.
At major hubs outside the U.K., it’s a mixed (transparent plastic) bag. Some airports, such as Amsterdam Airport Schiphol (AMS), use next-generation scanning technology that allows liquids and laptops to stay in carry-on bags—though bottles of liquids must still be under the 100-milliliter limit. But at Paris–Charles de Gaulle (CDG), the old rules apply: Liquids must be under the 100-milliliter limit, in their own plastic bag, and removed from carry-on luggage.
Is the liquids limit on the way out in the U.S.?
Across the Atlantic in the United States, the Transportation Security Administration (TSA) has not indicated that it plans to fully eliminate the “3-1-1 rule” that only liquids that fit into 3.4-ounce containers are allowed to remain in carry-on when passing through security. But it could be on the way out: The agency is “aggressively weighing” changes to the rule, Adam Stahl, TSA chief of staff, said at the Skift Global Forum, a major travel conference, in September 2025.
For now, the rollout of new CT scanning technology and other programs that allow liquids to stay in bags and shoes to stay on, such as TSA PreCheck, have sped up the screening process and security lines at TSA security checkpoints at a growing number of U.S. airports. In 2025, the TSA also lifted the 20-year rule requiring passengers to remove shoes.
Passengers can take advantage of various programs that allow them to clear security faster and more easily. TSA PreCheck, one of the most well-known and popular, allows passengers to keep their shoes on and liquids and electronics in their bags, and its new Touchless ID program (which has expanded to more than 60 U.S. airports) means passengers can pass through security even faster using facial recognition technology. Meanwhile, families can take advantage of the Families on the Fly program introduced in 2023, which offers passengers traveling with small children a designated security lane (but standard liquid limits still apply, unfortunately, unless you’re carrying formula or other accepted items).
