“Just a splash and you’ll taste the difference.” 

Straight off the bottle:

“Why are Bourbons made in Kentucky? Kentucky’s limestone aquifer produces a pure, velvety smooth water with hints of calcium and magnesium that is ideal for making Bourbon…and it’s found nowhere else. Ordinary tap water contains iron, which turns a Bourbon mash black. Not Old Limestone. Old Limestone brings out the taste of your favorite brand, never alters it.”