Why Does Sparkling Water Have a Taste or Smell?

Formation of Carbonic Acid

When carbon dioxide (CO₂) dissolves in water, it forms a weak carbonic acid (H₂CO₃). This gives sparkling water its characteristic slightly sour taste, which may seem unusual or even "chemical," especially when using distilled or highly purified water.

Contamination Inside the Soda Maker

If a soda maker has not been cleaned for a long time, especially after carbonating sweet beverages or liquids containing fruits and berries, bacteria and mold may develop on internal surfaces, valves, and tubing. Carbonation can make these odors much more noticeable.

Common Unwanted Odors and Flavors

Rotten egg smell — usually indicates the presence of hydrogen sulfide. It is most common in well water or water containing sulfur bacteria.

Chemical odor — may indicate contamination of the water source or water supply system.

Salty taste — often caused by elevated levels of sodium and/or magnesium salts.

Metallic taste or smell — typically indicates high concentrations of iron and manganese.

Musty, earthy, or moldy taste — may result from decaying vegetation in water sources or byproducts of fungal activity.

CO₂ Quality

Carbon dioxide (CO₂) itself is odorless. However, its interaction with water changes how flavors are perceived.

We refill and exchange carbonation cylinders using food-grade carbon dioxide (CO₂) of the highest quality. The gas quality is confirmed by a certificate of analysis and complies with DSTU 4817:2007 requirements.

What Affects the Taste and Smell of Sparkling Water?

The purification level, mineral composition, and total dissolved solids (TDS) of water have a significant impact on the taste of carbonated beverages.

As CO₂ dissolves in water, carbonic acid (H₂CO₃) is formed, lowering the pH. Whether this acidity tastes refreshing and pleasant or sharp and aggressive depends largely on the original mineral composition of the water.

What Is TDS?

TDS (Total Dissolved Solids) represents the total amount of dissolved minerals, salts, and trace elements in water.

Measurement units: ppm or mg/L (1 ppm = 1 mg/L).

How it is measured: using a TDS meter, which evaluates the electrical conductivity of water.

What it indicates: a high TDS value means highly mineralized water, while a low TDS value indicates very soft or nearly distilled water.

1. Water Purification: Reverse Osmosis vs. Tap Water

Tap Water or Poorly Filtered Water

May contain residual chlorine, organic compounds, and iron. Carbonation tends to enhance existing flavors and odors.

Result:

  • chlorine becomes more noticeable;

  • iron can create a stronger metallic taste.

Reverse Osmosis Water

Reverse osmosis removes up to 99% of impurities and significantly reduces mineral content.

Result:

  • the water may taste overly acidic;

  • the flavor can seem "empty" or flat;

  • carbonic acid is not buffered by minerals.

For this reason, remineralization is generally recommended before carbonation.

2. Mineral Content (TDS) and the Buffering Effect

The mineral content of water greatly influences the character of sparkling water.

Low Mineralization (<50 mg/L)

  • sharp, acidic taste;

  • more aggressive sensation from the bubbles.

Optimal Mineralization (100–300 mg/L)

  • balanced flavor profile;

  • minerals soften the effect of carbonic acid;

  • water tastes fresher and more pleasant.

High Mineralization (>600–1000 mg/L)

  • rich and distinctive flavor;

  • enhanced salty or soda-like notes;

  • typical of therapeutic mineral waters such as Borjomi.

Conclusions

  • Spring water or bottled table water with a mineral content of 150–250 mg/L and a good bicarbonate balance usually provides the most familiar sparkling-water taste.

  • If reverse osmosis water is used, a remineralization cartridge is highly recommended, especially one adding calcium and bicarbonates.

  • Colder water (ideally around +4°C / 39°F) dissolves CO₂ more effectively.

  • Cold water produces finer, more pleasant bubbles and helps maintain carbonation longer.