Sulphate, alkaline or saline?
A sparkling water is still water with carbon dioxide gas added. CO2 added to water has the effect of lowering the pH; in other words, making the water more acidic on the palate. Compare a still and sparkling water from the same producer; the increased acidity of the sparkling water should be very evident.
A water with a very low mineral content, such as water from the Western Cape, has a total dissolved solids (TDS) or mineral content of less than about 50 to 80 milligrams per litre (the main minerals are sodium and chloride). The pH of these waters is also often less than 7. As a result, the sparkling version of this type of water is this quite acidic on the palate. In addition, because of the low TDS, it has a low taste profile and its ‘freshness’ therefore gives an impression of drinking water from a high mountain stream.
An alkaline water is a water which contains calcium, and often magnesium, as the predominant dissolved minerals. These raise the pH and alkalinity of the water to provide a broad and full-bodied mouthfeel. In the sparkling version, this water is quite complex and will accompany many different dishes.
A sulphate water is one that has high levels of sulphate, often accompanied by magnesium. This water has a hint of bitterness, which most people find attractive and will match creamy and sweetish dishes. In South Africa, this is a water that is seldom encountered.
Source: Water on the Table – A guide to serving and drinking bottled water: Jenna Gough & John Weaver