Carbonated water

Carbonated water is simply water that has carbon dioxide gas dissolved in it. This can happen naturally through geological processes or be done artificially by injecting the gas under pressure. The dissolved gas creates small bubbles, giving the water a fizzy, effervescent quality. Common types include sparkling natural mineral water, club soda, and commercially produced sparkling water.

Some sparkling waters, such as club soda or certain mineral waters, contain added or naturally occurring minerals like potassium bicarbonate, sodium bicarbonate, sodium citrate, or potassium sulfate. In manufactured waters, these minerals are added to mimic the flavor profile of natural mineral waters and to counteract the acidity that comes from dissolving carbon dioxide, which creates a fizzy sensation. These products are sold in bottles and cans, and can also be made on demand using commercial carbonation systems in bars and restaurants, or at home with a carbon dioxide cartridge.

The first person believed to have aerated water with carbon dioxide was William Brownrigg in the 1740s. Joseph Priestley later invented carbonated water independently and by accident in 1767, while suspending a bowl of water above a beer vat at a brewery in Leeds, Yorkshire. He described the "peculiar satisfaction" he got from drinking it, and in 1772 published a paper called *Impregnating Water with Fixed Air*. Priestley’s apparatus, which used a bladder to regulate carbon dioxide flow between a generator and an absorption tank—similar to one used by Henry Cavendish five years earlier—was soon followed by many other designs. However, large-scale production of artificial mineral water did not begin until 1781, when companies specializing in it were established. The first factory was built by Thomas Henry of Manchester, England, who replaced the bladder in Priestley’s system with large bellows.

Priestley’s discovery eventually led to the soft drink industry, which started in 1783 when Johann Jacob Schweppe founded Schweppes to sell bottled soda water. Priestley himself did not profit financially from his invention. He did receive scientific recognition, however, when the Council of the Royal Society awarded him the Copley Medal at their anniversary meeting on 30 November 1773.

**Composition**

Both natural and manufactured carbonated waters may contain small amounts of sodium chloride, sodium citrate, sodium bicarbonate, potassium bicarbonate, potassium citrate, potassium sulfate, or disodium phosphate. These minerals occur naturally in some mineral waters but are added artificially to commercial products to mimic natural flavor and offset the acidity from carbon dioxide, which forms a low-pH (5–6) carbonic acid solution when dissolved in water. Naturally effervescent mineral waters come from artesian wells in places like Mihalkovo in the Bulgarian Rhodope Mountains, Medžitlija in North Macedonia, and most famously Selters in the German Taunus mountains.

**Health effects**

On its own, carbonated water appears to have little to no effect on health. It does not seem to impact gastroesophageal reflux disease, and there is tentative evidence that it may help with constipation in people who have had a stroke.

**Acid erosion**

Although carbonated water is somewhat acidic, saliva can partially neutralize this acidity. One study found that sparkling mineral water is slightly more erosive to teeth than non-carbonated water, but it is about 1% as corrosive as soft drinks.

**Chemistry and physical properties**

When carbon dioxide dissolves in water, a small amount of carbonic acid (H₂CO₃) forms, with the concentration of carbonic acid being about 0.17% that of CO₂. This acid gives carbonated water a slightly tart flavor. Its pH, between 5 and 6, is roughly between that of apple juice and orange juice, but much less acidic than stomach acid. A healthy human body maintains pH balance through acid–base homeostasis and is not materially affected by drinking plain carbonated water. Carbon dioxide in the blood is expelled through the lungs. Alkaline salts like sodium bicarbonate, potassium bicarbonate, or potassium citrate can increase pH.

The amount of gas that can dissolve in water follows Henry’s law, which depends on temperature. During carbonation, water is chilled—ideally to just above freezing—to maximize the amount of carbon dioxide that can dissolve. Higher gas pressure and lower temperature increase dissolution. When the temperature rises or pressure drops (as when a container is opened), carbon dioxide effervesces and escapes from the solution. Carbonated water is slightly denser than pure water, and its volume can be calculated by taking the volume of the water and adding 0.8 cubic centimeters for each gram of CO₂.

**History**

Many alcoholic drinks, such as beer, champagne, cider, and spritzer, were naturally carbonated through fermentation. In 1662, Christopher Merret created sparkling wine. William Brownrigg appears to have been the first to produce artificial carbonated water, in the early 1740s, using carbon dioxide from mines. In 1750, Frenchman Gabriel François Venel also produced artificial carbonated water, though he misunderstood the nature of the gas. In 1764, Irish chemist Dr. Macbride infused water with carbon dioxide during experiments on fermentation and putrefaction. In 1766, Henry Cavendish devised an aerating apparatus that later inspired Joseph Priestley.