If you spend a whole day in the city you will see it constantly: flasks under an arm, jugs on the ground beside a chair, a guampa passing from hand to hand on a bench in the shade.
01 What it actually is
Tereré starts from the same yerba as mate, but everything else changes. The guampa is filled with yerba, a bombilla — a metal straw with a filter — is planted in it, and very cold water is poured over, never hot.
The water does not go in plain. It is prepared beforehand in a jug or flask with fresh herbs, sometimes with lemon, and left to chill. That set of herbs has its own name in Guaraní: pohã ñana.
The herbs are crushed in a wooden mortar just before going in. Each is credited with a different purpose according to popular knowledge passed down in families, and the choice varies with the person, the hour and the heat of the day.
02 The codes, which do exist
One person pours: they fill the guampa, serve and pass it. The same guampa and the same bombilla circulate through the whole group, each person drinks until it makes the empty sound and hands it back to the pourer. You do not skip along the circle or serve yourself.
Nor do you stir the bombilla or move it around: it is set to filter properly and moving it ruins the round. And saying thank you means you have had enough, so it is best not to say it too early.
There is even a word for what you eat first: tereré rupá, literally the tereré's bed, a bite taken so as not to start on an empty stomach.
03 Why cold, and why here
The most direct explanation is the climate. In January the average high is around thirty-four degrees and the absolute record exceeds forty-two. In that heat, a boiling infusion is not a reasonable option.
The second explanation is cultural. The habit of mixing yerba with medicinal herbs comes from a much older Guaraní knowledge, and that crossing is what makes tereré something other than a cold mate.
In 2020 UNESCO inscribed these practices and knowledge on its representative list of intangible cultural heritage. It was not the drink that was recognised: it was the circle, the sharing and the conversation around it.
04 How to try it without looking odd
The easiest route is buying the basic kit — guampa, bombilla and flask — in any shop downtown, and the herbs from a yuyos stall. That is where you actually learn: you ask for something for the heat, for the stomach, or just for whatever they recommend.
If you are invited into a circle, the only rule that matters is not to break the turn. Drink to the end, give the guampa back to the pourer and do not hold on to it while you talk: the round has its own rhythm and you notice when it stops.
And do not expect it to taste sweet. It is bitter, very cold and quite herbal. The first guampa is disconcerting; the third, with thirty-four degrees outside, makes perfect sense.
05 What it reveals
Tereré explains something about the country that monuments do not show: here shared time has a concrete physical form, with a schedule, an object and rules. Sitting in the shade passing a guampa is not a break from the day, it is part of the day.
