Drinking water, including bottled water, may, under federal regulations contain some small amounts of some contaminants. The presence of some contaminants does not necessarily indicate that water poses a health risk. Some are harmless and may not effect either taste or quality, whereas others may be life threatening. EPA sets standards for approximately 90 contaminants in drinking water. EPA's standards, along with each contaminant's likely source and health effects, are available at free here. More detailed information on specific contaminants is available below:
Microbes ~ Radionuclides ~ Inorganics ~ Volatile Organics ~ Synthetic
Organics ~ Disinfectants ~ Disinfection Byproducts ~ MTBE ~ Health Advisories
Coliform bacteria are common in the environment and are generally not harmful. However, the presence of these bacteria in drinking water is usually a result of a problem with the treatment system or the pipes which distribute water. It indicates that the water may be contaminated with other germs that can cause disease.
Fecal Coliform and E coli are bacteria whose presence indicates that the water may be contaminated with human or animal wastes, such as infiltration from farm drain off, human septic tanks, or sewage spills into drinking water supplies, such as rivers. Microbes in these wastes can cause short-term effects, such as diarrhea, cramps, nausea, headaches, or other symptoms.
Turbidity has no health effects. However, turbidity can interfere with disinfection and provide a medium for microbial growth. Turbidity may indicate the presence of disease causing organisms. These organisms include bacteria, viruses, and parasites that can cause symptoms such as nausea, cramps, diarrhea, and associated headaches.
Cryptosporidium is a parasite that has been in the news quite a lot in recent years. It enters lakes and rivers through sewage and animal waste. It causes cryptosporidiosis, a mild gastrointestinal disease. However, the disease can be severe or fatal for small children and people with severely weakened immune systems. EPA and CDC have prepared advice for those with severely compromised immune systems who are concerned about Cryptosporidium.
Giardia lamblia is a parasite that enters lakes and rivers through sewage and animal waste. It causes gastrointestinal illness (e.g. diarrhea, vomiting, cramps).
Yes, certain radioactive substances may find their way into your drinking water! Many of these are present in the ground from which well waters are drawn. Radon is the most common radioactive isotope contaminant.
Certain minerals are radioactive and may emit a form of radiation known as alpha radiation. Some people who drink water containing alpha emitters in excess of EPA's standard over many years may have an increased risk of getting cancer.
Beta/photon emitters. Certain minerals are radioactive and may emit forms of radiation known as photons and beta radiation. Some people who drink water containing beta and photon emitters in excess of EPA's standard over many years may have an increased risk of getting cancer.
Combined Radium 226/228. Some people who drink water containing radium 226 or 228 in excess of EPA's standard over many years may have an increased risk of getting cancer.
Radon gas can dissolve and accumulate in underground water sources, such as wells, and in the air in your home. Breathing radon can cause lung cancer. Drinking water containing radon presents a risk of developing cancer. Radon in air is more dangerous than radon in water.
Technical fact sheets on Inorganic Contaminants
Arsenic. Some people who drink water containing arsenic in excess of EPA's standard over many years could experience skin damage or problems with their circulatory system, and may have an increased risk of getting cancer.
Fluoride. Many communities add fluoride to their drinking water to promote dental health. Each community makes its own decision about whether or not to add fluoride. EPA has set an enforceable drinking water standard for fluoride of 4 mg/L (some people who drink water containing fluoride in excess of this level over many years could get bone disease, including pain and tenderness of the bones). EPA has also set a secondary fluoride standard of 2 mg/L to protect against dental fluorosis. Dental fluorosis, in its moderate or severe forms, may result in a brown staining and/or pitting of the permanent teeth. This problem occurs only in developing teeth, before they erupt from the gums. Children under nine should not drink water that has more than 2 mg/L of fluoride.
Lead typically leaches into water from plumbing in older buildings. Lead pipes and plumbing fittings have been banned since August 1998. Children and pregnant women are most susceptible to lead health risks. For advice on avoiding lead, see EPA's lead in your drinking water fact sheet.
Synthetic Organic Contaminants,
Di 2-ethylhexyl adipate
Di 2-ethylhexyl phthalate
PCBs [Polychlorinated biphenyls]
Technical fact sheets on Synthetic Organic Contaminants
Volatile Organic Contaminants