I personally dont drink whisky with any water.
The way it was bottled was the way it was intended to behave to your nose and palate by the distillery. Adding any water is going to take away the hard work they put into deciding how it was going to behave.
Not only that, but the water you are putting in will be totally different from the water they make the whisky with, and will impair the taste. Especially if it's from the tap.
When Dave Stewart takes the time and effort to decide to bottle 15yo Balvenie Single Barrel at 47.8% and you plonk a load of tap water in it, you've undone all that work
Add a little bit if you want to start getting into whisky, but you need to get your mouth used to the high alcohol content, because after a while you will just start quaffing down A'bunadh's neath (60%)
.....and get a bottle of Balvenie Doubelwood instead. Smoother and the sweetness and finesse will help you much more than chucking water into Glenlivet.