The sources of drinking water (both tap water and bottled water) include rivers, lakes, streams, ponds, reservoirs,
springs, and wells. As water travels over the surface of the land or through the ground, it dissolves naturally-occurring
minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or
from human activity.
Contaminants that may be present in source water include the following:
* Microbial contaminants, such as viruses and bacteria that may come from sewage treatment plants, septic systems,
agricultural livestock operations, and wildlife.
* Inorganic contaminants such as salts and metals, which can be naturally occurring or result from urban storm runoff,
industrial or domestic wastewater discharges, oil and gas production, mining, or farming.
* Pesticides and herbicides, which may come 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 by-products of
industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, and septic
systems.
* Radioactive contaminants, which can be naturally occurring or be the result of oil and gas production and mining
activities.
In order to ensure that tap water is safe to drink, EPA prescribes regulations that limit the amount of certain
contaminants in water provided by public water systems. Food and Drug Administration regulations establish limits for
contaminants in bottled water which must provide the same protection for public health.