Tip #2: Reduce waste and save some money by bringing a reusable water bottle. So you can't bring H₂0 or any other liquids more than 3.4 oz. (well there are some exceptions) through security, but you CAN bring an empty bottle. Just fill it up on your way to boarding your flight after screening.

You cannot bring a filled reusable water bottle through the security checkpoint in most international airports, including those in the U.S., UK, and EU, due to the "3-1-1" liquids rule. Any container holding more than 3.4 ounces (100ml) of liquid will be confiscated by security agents, regardless of whether it is water, a smoothie, or a soft drink. To get around this, you should bring your reusable bottle empty through the security line. Once you have cleared the checkpoint and entered the "airside" of the terminal, you can fill your bottle for free at the various hydration stations or water fountains found near the restrooms. Bringing an empty bottle is a major travel hack in 2026, as it saves you the exorbitant cost of airport bottled water (often $5–$7) and ensures you stay hydrated during the flight without relying on the small plastic cups provided by the cabin crew. Some newer high-tech "CT scanners" in select European airports are beginning to allow larger liquids, but until this technology is universal, the "bring it empty" rule remains the only guaranteed way to keep your bottle.