If you want a cold drink that isn't sweet, your choices are pretty much alcohol, alcohol-free alternative, water.
Kvaas contain alcohol, doesn’t it?
I think only as much as kombucha, not enough to cause a buzz
I did almost mention jaljeera, but thought that might be a bit niche. It is also often sweetened though. I've never known not-sweet lassi though? Salted lassi is still sweet underneath, like salted caramel, ime. We could count it with the sweet-ish milk drinks, anyway.
Uh, no.
There's also seltzer, flavored seltzer, flavored water, iced tea, iced coffee, herbal infusions (like hibiscus, rooibos, honeybush, etc), broth, milk and plant based milk alternatives, and fermented drinks like kombucha + kefir. That's just off the top of my head.
Hibiscus even has the benefit of helping regulate blood pressure.
I almost never drink sweet drinks or plain water and rarely drink alcohol. My fluid consumption is almost entirely: hot tea, iced tea, kombucha, and hibiscus infusion. Sometimes seltzer. Sometimes coffee.