Steve
Adding water is very important, but generally a good blended whisky already contains sufficient water to obtain the optimum flavour, Chivas Regal being a good example.
By adding a few drops of water to a whisky, you can open up different, new and subtle flavours that you previously had not experienced. This is especially true when drinking cask strength whiskies that have higher alcohol levels (these can be up to and over 60% in some cases).
With cask strength whisky the alcohol and resulting burning in your mouth can overpower even the most prominent flavours. By adding some water, this dilutes the alcohol and reduces its effect, giving both the prominent and more subtle flavours a chance to shine.
I have cask strength Laphroag for example and moderate the harshness to my own optimum.
Scotland is split down the middle with the peaty whiskies in the West and in the isles, and the more delicat Speyside whiskies in the East, Spey side also has some cracking roads.
A strength cask Macallan and a jug of highland water would be perfect for a taste test.
Remember the age question to be safe to drink the whisky must spend 8 years in the cask, all single malts are 10 year old, generally the best flavours are developed after 15 years in the cask.