The Highland Spring source, fabled since 1503 and King James IV of Scotland, comes from the Ochil Hills regional formation of red sandstone and basalt. This formation is some 400 million years old, and encompasses the nearby Gleneagles source also. The water quality results from a long-term filtration of fresh rainwater from the undulating heather clad slopes. Highland Spring is even lower in minerals than Gleneagles - virtually Sodium-free, and Nitrate-free. It is one of the elite low-TDS natural mineral waters on earth.