True whiskey connoisseurs say that adding a couple of drops of water to a glass improves and enhances the drink's taste. This may seem counterintuitive, and logic would dictate that it's just watering down the flavor, but there is a scientific explanation as to why water is added to a glass of whiskey.
Guaiacol, a compound partially responsible for the peaty smell and flavor of scotch whiskey, is more present at the surface of the whiskey when water is added, making it easier for the nose and palate to experience the flavor and smell it imparts on the drink. Scientists also report that this reaction occurs when the percentage of alcohol is lowered by the water.
Most whiskey lovers just "wing it" when it comes to how much water is best to add, but because different whiskeys have different alcohol contents, the amount of water used can also vary. Some entrepreneurs have begun selling pure Kentucky stream water to be mixed with bourbon, as tap water is not recommended.
Another good water source is Uisge Source Water of Scotland which offers three types of water from three different Scotland regions, and the bottle comes with a dropper used for adding water to whiskey. Fancy droppers have also come on the market in recent years, but a generic rubber-topped eyedropper works excellent too.