How Can You Navigate the Unique TSA 3-1-1 Rule and Explore U.S. Airports Like a Pro?

Published on June 16, 2025

The Transportation Security Administration (TSA) has long adhered to the 3-1-1 liquid rule, which mandates that airline passengers can only bring liquids in containers of 3.4 ounces (or 100 milliliters) or less, placed in one clear quart-sized bag. This rule, implemented following a thwarted explosive plot in 2006, is intended to enhance security by limiting the amount of liquid a passenger can carry through security checkpoints. However, there are certain exceptions to this rule, allowing passengers to carry larger amounts of liquid in specific circumstances.

While the 3-1-1 rule is widely known, there are instances where full-size liquids can be carried through airport security. The TSA has outlined several exceptions to this rule, ranging from medications to baby formula and duty-free items. Here’s a detailed breakdown of the exceptions and what passengers should know when traveling with liquids.

TSA Liquid Rule Explained

The 3-1-1 rule states:

• 3: Each container of liquid, gel, aerosol, cream, or paste must be 3.4 ounces (100 milliliters) or less.
• 1: All liquids must be placed in a single, clear, quart-sized, zip-top plastic bag.
• 1: Each passenger is limited to one of these quart-sized bags.

This rule applies to common travel items like shampoo, toothpaste, sunscreen, and even peanut butter. Any liquid or gel beyond this limit must be packed in checked luggage. However, certain liquids are exempt from this limitation under specific conditions.

Medical and Health-Related Exceptions

One of the most common exceptions to the 3-1-1 rule is for prescription liquids, gels, and aerosols. If you have medically necessary liquids that exceed the 3.4-ounce limit, TSA allows you to bring them through security with the following conditions:

• Proper labeling: Containers must be clearly labeled to identify the contents.
• Screening methods: Security officers may opt to screen these items visually, via X-ray machines, or by conducting explosive trace tests.
• Additional screening: If necessary, TSA may ask you to open the container for vapor analysis. Passengers can request alternative screening options if they prefer not to open their containers.

Some medications may require additional screening such as AIT screening, pat-downs, or an inspection of carry-on property. It’s important for passengers to inform TSA officers about any medical necessities to avoid delays or complications.

Interestingly, wet pet food for service animals, even if medically necessary, is not exempt from the liquid rule. TSA does not allow this exception.

Infant and Child Care Provisions

For parents traveling with babies, the TSA allows unlimited quantities of breast milk and infant formula through security, provided these items are considered medically necessary. You do not need to have the baby with you to qualify for this exemption.

• Breast milk and formula: TSA recognizes these as medically necessary and allows them to exceed the normal liquid limits.
• Transportation: To ensure smooth screening, the TSA suggests transporting liquids in clear, translucent bottles. For pouches or other packaging, alternative screening methods may be required.
• Baby food and drinks: Items like puree pouches, baby food jars, and water for babies are also exempt, but additional screening may apply.

TSA will not limit the amount of water for babies, and bottles or containers used to carry these liquids should be presented separately for screening.

Temperature-Controlled Items

Passengers traveling with medically necessary gel ice packs, frozen water bottles, or similar items need not worry about the 3-1-1 restrictions as long as these items are frozen solid at the time of screening.

• Gel ice packs and freezer packs: These can pass through security as long as they are frozen.
• Frozen water bottles: Similarly, frozen water bottles are permitted. However, partially melted items, or slushy portions, are counted as liquids and will be subject to the 3-1-1 rule.

If a gel ice pack is medically necessary, TSA permits it even if it is partially melted. Other medical items like IV bags, pumps, syringes, and medical supply accessories are also allowed through security with appropriate documentation.

Food and Biological Specimens

There are various exceptions for food items and biological specimens that may be carried through airport security, despite their liquid or semi-liquid nature.

• Fresh eggs: Even though they contain liquid yolks, fresh eggs can be brought through security, as long as they are separated from other carry-on bags for proper X-ray screening.
• Live fish: Live fish and other similar items, like coral, are allowed if they are carried in transparent, clear containers for proper inspection.
• Scientific specimens: Non-infectious biological specimens, such as those preserved in formaldehyde, ethanol, or isopropanol, are permitted for scientific research. However, specific packaging requirements apply, limiting the liquid to 30 milliliters in sealed inner plastic bags and 1 liter in outer packaging.

In the case of live lobsters, passengers must seek advance airline approval to transport them in clear, plastic, spill-proof containers.

Electronic Equipment Exceptions

When traveling with electronic equipment that contains wet batteries, such as gel cells or absorbed glass mat batteries, passengers can bring them through security without issue. However, there are specific conditions that must be met:

• Non-spillable batteries with absorbed electrolyte are allowed.
• Battery voltage must be limited to 12 volts or less, and the capacity must be under 100 watt-hours.

The equipment must also be designed to prevent accidental activation or excessive heat generation.

International Duty-Free Purchases

One of the most well-known exceptions to the 3-1-1 rule involves duty-free purchases. Items like alcohol, wine, or maple syrup that are bought at international duty-free shops are exempt from the normal liquid limits, but only under certain conditions.

• Sealed tamper-evident bags: Duty-free liquids purchased at international airports or aboard international flights must be packed in tamper-evident bags that are sealed properly by the retailer.
• Sealed packaging: These bags must remain untampered throughout the entire travel journey to ensure the safety of the liquid contents.
• Inbound international flights: U.S. travelers can only take advantage of this exemption when returning from an international flight.

The International Civil Aviation Organization (ICAO) developed this exemption system in 2008 to maintain liquid security measures while still allowing for duty-free shopping.

Screening Process and Officer Discretion

It’s important to note that the TSA officers have discretion over the final decision on whether a liquid item is allowed through security. All oversized liquids must be placed in a separate bin or dish for further inspection. If any item triggers a security alarm, it will undergo additional inspection regardless of whether it’s within the approved limits.

Passengers are advised to inform TSA officers ahead of time if they are carrying larger liquids, as this can help speed up the screening process and reduce delays. Final determinations regarding the approval of liquid items depend on the discretion of the individual security officer and may vary by situation.

Conclusion

The TSA’s 3-1-1 rule plays a crucial role in maintaining airport security, but it’s essential to understand that there are numerous exceptions for passengers carrying medically necessary liquids, food items, biological specimens, and duty-free purchases. While passengers are generally required to comply with the liquid limits, the TSA provides flexibility to accommodate travelers’ unique needs and ensure a safe and smooth journey.

For travelers, the key is knowing what exceptions apply to their situation and being prepared for additional screening or documentation when needed. By understanding the nuances of the 3-1-1 rule and its exceptions, passengers can avoid delays and make their travel experience as efficient as possible.

Key Takeaways:

• 3-1-1 rule: Liquids must be in containers of 3.4 ounces or less, placed in one quart-sized bag.
• Medical exceptions: Prescription liquids, baby formula, and some food items are exempt from the 3-1-1 rule.
• Duty-free: Liquids purchased at duty-free shops are exempt if properly sealed in tamper-evident bags.
• Officer discretion: TSA officers have the final say on whether oversized liquids are allowed through security.