Microbiological contaminants (bacteria, viruses, protozoan, etc.) can come from sewage treatment plants, septic systems, agricultural live stock operations, and wildlife.
Inorganic chemical contaminants, such as salts and metals, which can be naturally occurring or result from urban stormwater run off, industrial and/or domestic wastewater discharges, oil and gas production, mining, or farming.
Pesticides and herbicides which may occur from a variety of sources such as agriculture, urban stormwater runoff, and residential uses.
Organic chemical contaminants, including synthetic and volatile organic chemicals, which are byproducts of industrial processes and petroleum production, and can also come from gasoline stations, urban stormwater runoff, and septic systems.
Radioactive contaminants, which can be naturally occurring or be the result of oil and gas production, or mining activities.