Aluminum is a trivalent cation found in its ionic form in most kinds of animal and plant tissues and in natural waters everywhere.
[1] It is the third most prevalent element and the most abundant
metal in the earth's crust, representing approximately 8% of total mineral components.
[2] Due to its reactivity, aluminum in nature is found only in combination with other elements.
Dietary aluminum is ubiquitous but in such small quantities that it is not a significant source of concern in persons with normal elimination capacity.
Urban water supplies may contain a greater concentration because water is usually treated with aluminum before becoming part of the supply. Subsequent purification processes that remove organic compounds take away many of the same compounds that bind the element in its free state, further increasing aluminum concentration.