Certain rare geological conditions can produce naturally carbonated water. The origin of the CO2 is either organic matter degradation, interaction with carbonates, metamorphic devolatilization, or magmatic degassing (volcanic activity). The slow process of natural carbonation in geology is very complex. It leads to a natural product with very distinct characteristics compared to more straightforward and faster artificial carbonation.
Naturally carbonated waters have historically been highly sought after for their supposed curative properties. The carbon dioxide helps this water absorb minerals at high levels. Gerolsteiner is an example of a naturally carbonated water. Volcanic activity in the Eifel region of Germany enriches the water there with minerals, and magma gives off carbon dioxide. Other naturally carbonated waters include Badoit, Vilajuïga, Pedras, Wattwiller, Ferrarelle, and Borsec. Perrier and Cana Royal also have unique carbonation stories.
Even among the natural carbonated waters, there is a difference in how the water from such a unique source is bottled. Ideally, you want a gentle bottling process with as little disturbance to the water as possible. Unfortunately, in a factory bottling process, the carbonation is easily lost, especially at low levels of original carbonation. Even so, the water is carbonated when it emerges, there would be almost no carbonation in the bottle after the water passed through the filling machines.
The solution is capturing the water and the carbonic gas separately in the aquifer. The two substances are taken from the same geological formation, but they're extracted at different depths. The gas is then filtered before being added back to the water. When you open such a bottle, the source of the carbonation is from the original source, but the carbonation level is usually elevated.
From the waters featured in our book, Cana Royal (Slovenia) and Cambuquira (Brazil) are the only waters that bottle natural carbonated water without separating CO2 from the water in the bottling process. The superfine and soft bubbles in the bottle are identical to the character of the water at the source — an extraordinary experience.
Like an old married couple, the CO2 in natural carbonated water has been with the water and its dissolved minerals for ages. Even when separated for a little while in the bottling process, they enjoy being together in the bottle again. You'll notice this if you open a bottle of naturally carbonated water and pour it into a glass. The bubbles stay much longer in the glass and bottle. Natural carbonated waters are chemically very different from forcefully carbonated waters. In our example, the artificial carbonation is like a shotgun marriage and, when you open the bottle, the two parties — CO2 and H2O — want a separation and the carbonation disappears rather quickly.
