Contaminants

The Safe Drinking Water Act defines the term “contaminant” as meaning any physical, chemical, biological, or radiological substance or matter in water. Therefore, the law defines “contaminant” very broadly as being anything other than water molecules. Drinking water may reasonably be expected to contain at least small amounts of some contaminants. Some drinking water contaminants may be harmful if consumed at certain levels in drinking water while others may be harmless. The presence of contaminants does not necessarily indicate that the water poses a health risk. (source: EPA)

Organic: Herbicides, Pharmaceuticals
Inorganic: Metals
Microorganisms: Bacteria, Virus, Cysts
Radionuclides: Radioactive compounds
Disinfectants/Disinfectant Byproducts