I know someone would immediately jump in with water if I didn't caveat that, haha. Tap water is the most frugal drink, yes I know, but for me plain ol' water more of a basic survival thing. And I like to be happy too, not stuck permanently in survival mode, even if I'm also being frugal.
So.
One of my "vices", if you can call it that, is fancy tea.
I'm American and we're not really a tea-drinking culture, so I was taken by surprise when I got into drinking tea and learned you can get surprisingly nice quality loose leaf tea online that blows grocery store tea bags out of the water, and it's not a terribly expensive habit. Grocery store tea in tea bags is basically 'tea dust' left over from processing better teas, and basically almost any loose leaf tea is a better quality than bagged tea dust, so you don't have to break the bank to see immediate improvement in your tea quality.
And that surprised the heck out of me!
I eventually realized that's because tea is a dry good and cheap to ship--it's light, dry, packs small, ships well. Much easier to get your hands on than, say, alcohol or liquid drinks that are heavy or distributed in glass bottles.
So yeah. It's not as frugal as water, but I found I can usually still have some nice tea around even if I'm pinching every penny, and it can help tide me through tough spots without the downsides of other vices (like drinking, smoking, etc.)
What are your guys' favorite frugal drinks?
Personally I feel it's closer to a non-carbonated soft drink. Probably because of the amounts of sugar, hah. It seems formulated more like a lemonade almost, just with tea as the flavor instead of lemons?