Deuterium-depleted water (DDW), also known as light water (or ”extra light water”, like our products, who have a very low Deuterium concentration) is water which has a lower concentration of deuterium than occurs naturally. In “Vienna Standard Mean Ocean Water” VSMOW (*) deuterium occurs at a rate of 155.76 ppm. All natural occuring water, like drinking water has deuterium levels around this value. (*) (VSMOW) is a water standard defining the isotopic composition of fresh water. Simply put, deuterium-depleted water is natural water cleared of most of its heavy, radioactive components thru an advanced technologial process. This is why deuterium-depleted water is called ”light water”.