Groundwater, the source of water for private wells, is never simply a pure combination of hydrogen and oxygen atoms (H20). It contains many impurities, reflecting the composition of the soils, sand, gravel, and rock through which it travels. Groundwater naturally contains:
- Dissolved minerals such as iron, calcium, magnesium, bicarbonate, chloride, and sulfate
- Gases such as carbon dioxide, oxygen, and nitrogen
- Dissolved organic compounds
As a result of human activity, groundwater can also contain contaminants such as pesticides, nitrate
, metals, and volatile organic chemicals
(VOCs). Any chemicals that are used or disposed of (purposely or accidentally) on the land surface have the potential to find their way into groundwater supplies.