Water. The water used in most distilleries is soft. It is common wisdom that the best water sources are those that rise from granite over peat. The flavour the source water picks up from its journey is concentrated by the distillation process.
Peat. The amount and character of peat used in the kilning process has a pronounced effect on the flavour of the whisky.
Stills. The shape of the pot still , the angle of the lyne arm that leads to the condensing unit, as well as the degree of heat applied affect the flavours that are captured in the distilled whisky. Taller stills tend to produce lighter whiskies.
Casks. Whisky will usually spend 8 to 15 years in an oak cask. The type of wood used and the micro-climate of the maturation warehouse have a profound influence on the character of the whisky. Most casks are made from American oak, some of which have previously been used for the storage of bourbon. Some distilleries used old sherry casks which impart a sherried flavour to the spirit. The traditional maturation warehouse is damp with earthen floors. The humidity cuts the rate of evaporation in the barrels. In some coastal distilleries the sea air is said to imbue a certain briny character to the whisky.