Health Effects

Health Effects of Some Common Drinking Water Contaminants
Total Coliform
Coliform bacteria is generally found in drinking water due to a problem with the water treatment or the pipes that distribute the water. The presence of coliform bacteria in your water may indicate possible contamination by disease-causing microorganisms. Although the coliform themselves are not harmful, their presence often indicates the presence of other forms of contamination which are harmful. Disease symptoms of consuming contaminated water may include diarrhea, cramps, nausea, and possibly jaundice, and any associated headaches and fatigue.

Fecal Coliform

Fecal coliform, also known as Escherichia coli or E Coli, is a particular type of coliform bacteria. Their presence in drinking water is more serious than other coliform bacteria because they are disease-causing microorganisms. Acute exposure to this type of contamination can cause severe diarrhea, cramps, and nausea. Because fecal coliform contamination is more severe than contamination by other types of coliform bacteria, EPA sets an acute standard indicating that for water to be considered safe it must be free of all fecal coliform.


Exposure to nitrate in drinking water above the current EPA standard of 10 ppm poses an acute risk to infants of methemoglobinemia, or blue baby syndrome, a condition caused by lack of oxygen. Symptoms of methemoglobinemia include shortness of breath, nausea, vomiting, diarrhea, lethargy, and in more extreme cases loss of consciousness, and even death. In addition, nitrate reacts with other chemicals in the gut to form nitrosamines, potent carcinogenic compounds.

Gross Alpha Radioactivity

is a measure of radioactivity in water. Its presence indicates contamination by radium, radon, uranium, or other naturally occurring radioactive substances. These substances are known human carcinogens. The EPA estimates that over a lifetime 15,750 people get cancer from drinking radioactive water (EPA 1991).

Radium-226 and -228

is another measure of radioactivity in water. Radium, a byproduct of the decay of uranium, is a naturally occurring, radioactive metal. It is a human carcinogen. Radium-226 is associated with bone sarcomas and head carcinomas, and Radium-228 is associated with bone sarcomas. EPA estimates that, over a lifetime, 15,750 people get cancer from exposure to radioactive drinking water (EPA 1991). Recommended treatment techniques include lime softening, cation exchange, and reverse osmosis.

Total Trihalomethanes

Trihalomethanes, (THMs) are disinfection byproducts, or in other words, they are chemicals that are formed when the chlorine used to disinfect your drinking water reacts with naturally occurring organic material in the water. More than ten human epidemiological studies have indicated that these chemicals are associated with rectal, bladder, or pancreatic cancers. A 1993 article in the American Journal of Public Health estimated that 10,700 rectal and bladder cancers might be caused each year by disinfection byproducts like the trihalomethanes (Morris, et al. 1992).

A 1993 study by the U.S. Public Health Service suggested that disinfection byproducts are also associated with birth defects, including spine and neural disorders (Bove, et al. 1992). The current EPA standard allows a TTHM concentration of 0.10 mg/l, although in 1987 the National Academy of Sciences recommended that this standard be made more stringent (NRC 1987). Trihalomethane concentrations can be reduced by keeping source water clean, and by reducing or eliminating the "precursors" to these hazardous chemicals (organic material in the water that is necessary for their production) using treatment technologies such as Granular Activated Carbon.


According to the Department of Health and Human Services, lead is the number one environmental threat to children. For years, many water pipes contained lead, and this lead continues to leach into drinking water. Lead can cause a variety of adverse health effects in humans at low levels of exposure, and the EPA has concluded that there is in fact no "safe" exposure to lead. Exposure to lead in drinking water causes interference with red blood cell chemistry, delays in normal physical and mental development in babies and young children, deficits in the attention span, hearing, and learning abilities of children, and increases in the blood pressure of some adults.

EPA has found that lead in drinking water causes over 560,000 children to exceed the CDC's blood-lead level of concern, and that better control of lead could help prevent over 680,000 cases of hypertension. Public water systems that have lead concentrations above 15 parts per billion, in more than 10 percent of samples, have exceeded EPA's Lead Action Level. They must then optimize corrosion control and engage in a public education program to inform consumers of ways they can reduce their exposure to lead in drinking water (NRDC 1993).


is an agricultural herbicide (commonly used on corn and soybeans) that is frequently found in drinking water. It is a possible human carcinogen, and has been found to cause cancer of the mammary gland in animal studies. In addition, atrazine has also been found to disrupt the hormonal and endocrine system. Exposure to atrazine above the MCL is a serious concern because the standard is particularly weak, allowing cancer risks that exceed the "negligible" risk standard by a factor of 18. EPA has placed atrazine into Special Review, the first step in a possible ban, due to concerns over the public health impacts of exposure in food and water.


is a probable human carcinogen. This chemical is commonly used in metal cleaning or dry cleaning, and it usually contaminates drinking water wells due to improper disposal.


During the 1993 cryptosporidium outbreak in Milwaukee (which sickened an estimated 403,000 people), an increase in turbidity was the only indication that there was a problem with drinking water quality. Highly turbid water indicates that the risk of disease from waterborne microorganisms is significantly increased. Turbidity is a measure of the clarity of a water sample and is used as an indicator for effectiveness of treatment processes to control pathogens in drinking water. In addition, high levels of turbidity may reduce the efficiency of disinfection and interfere with measurement of total coliforms.

Treatment Technique Violations

If water is inadequately treated, microbiological contaminants present in the water may cause diarrhea, cramps and nausea. Under the Surface Water Treatment Rule (SWTR), the EPA has set enforceable requirements for treating drinking water to reduce the risk from disease-causing microorganisms such as shigella, salmonella, cryptosporidium, and giardia. Under the SWTR, drinking water systems that filter their water must ensure that the process is working effectively as demonstrated by turbidity and objective disinfection criteria. Public water treatment systems that do not filter their water must ensure that their source waters are clean and adequately disinfected.