If you find yourself trudging through airports every week, as I often do, I don’t doubt you’ve noticed that bottled water doesn’t sell for less than $3. Quite often even that is cheap. Nearly ever week since January I’ve wandered through terminals searching for bottled water, and nearly every week I shout (in my head) “Damn, $4.50!”

I’m sure this tip has already been revealed elsewhere, but it only recently occurred to me and I feel it’s worthy enough to repeat: bring your empty water bottle through airport security, then fill it up at water fountains. Since I usually fly twice a week this saves between $6 to $8 dollars each week just in bottled water, or at least $240 to $320 per year if I fly about 40 weeks between January and December. Is it a mountain of cash? No, but hey, it looks nice in my pocket and it’s better for the environment, so that’s like a double bonus.

Of course this won’t work for everyone: first of all, this tip assumes there’s a reliable supply of safe drinking water wherever you’re traveling. If you fall into this category, or aren’t sure, I’d say play it safe and spring for bottled water – Montezuma’s revenge is no joke. Fellow travelers have also reported that larger water bottles (one liter and above) are often confiscated at security even if they’re bone dry, so keep that in mind.

If we stick with the environmentally friendly theme, I recommend something reusable like a Klean Kanteen or something similar. If not, many hotels provide complementary water bottles that work just fine.