Instead of purchasing an overpriced, single-use, plastic water bottle at the airport, bring a reusable water bottle whenever you fly. TSA and comparable regulations overseas restrict the amount of liquid you can take through security, so leave your bottle empty until you’re through. Once you’re past security, however, you can fill reusable water bottles at filtered water fountains, which are now available in most US airports. Bringing an empty reusable water bottle helps decrease plastic waste throughout your travels and even saves you money.