Drinking water comes from groundwater, wells, rivers, lakes, streams, and reservoirs. People in cities usually drink water from lakes, rivers, and reservoirs that is filtered and cleaned through water treatment plants. People in rural areas frequently drink water pumped from a private well. 

Every drinking water supply is affected by activities close by and many miles away. All water contains some impurities. The U.S. Environmental Protection Agency (EPA) sets acceptable limits for more than 80 contaminants that may be in drinking water and pose a risk to human health.

Drinking water can be contaminated by natural conditions and recreational activities, including marinas and boats. It can be contaminated by pesticides, fertilizers, animal waste, damaged septic systems, leaking underground storage tanks, landfills, mining, and industrial releases to air and water. Drinking water can also be contaminated by runoff from farms, storms, urban areas and industrial or construction sites. Endocrine disruptors can also be found in drinking water.

Waterborne diseases are a major human health concern because many people can be affected if a source of drinking water is contaminated. Bacteria and viruses can cause acute, or short-term, human health effects if they are found in drinking water at high levels. 

More serious, chronic health effects can occur if people consume a contaminant in drinking water at levels above EPA standards for many years. Contaminants that can have long-term health effects include solvents, radioactive elements, and minerals such as arsenic. Contaminated drinking water can cause chronic health effects such as cancer, liver or kidney problems, and reproductive problems.

This description is based on the information found in the Web links listed with this topic.

Web Links from MedlinePlus (National Library of Medicine)
Cryptosporidiosis
Drinking Water
E. Coli Infections
Food Safety
Foodborne Illness
Giardia Infections
Lead Poisoning
Parasitic Diseases
Traveler's Health
Water Pollution

More Links
Drinking Water Contaminant Candidate List (Environmental Protection Agency)
Drinking Water home page (Centers for Disease Control and Prevention)
Droughts and Health (National Library of Medicine)
National Water-Quality Assessment Program (US Geological Survey)
Office of Ground Water and Drinking Water home page (Environmental Protection Agency)
Pharmaceutical and Personal Care Products in Drinking Water Supplies (Groundwater Foundation)
Public Drinking Water Systems Programs (Environmental Protection Agency)
Radionuclides in Water (Environmental Protection Agency)
Water Pollution. Enviro-Health Links (National Library of Medicine)
Water-related Diseases and Contaminants in Public Water Systems (Centers for Disease Control and Prevention)

Chemicals in Drinking Water
Are these chemicals in MY community?
Acetone
Ammonia
Arsenic
Benzene
Bisphenol A (BPA)
Chlorine
Chromium
Diesel
Endocrine Disruptors
Formaldehyde
Gasoline
Lead
Mercury
Methanol
Perchlorate
Perchloroethylene (PCE, PERC)
Persistent Organic Pollutants (POPs)
Pesticides
Phthalates
Polybrominated Diphenyl Ethers (PBDEs)
Polychlorinated Biphenyls (PCBs)
Polyvinyl Chloride (PVC)
Propane
Radon
Solvents
Styrene
Volatile Organic Compounds (VOCs)

Last Updated: October 17, 2012