Drinking Water Contaminants

Mar 27th 2017

A contaminant is defined as any substance, naturally occurring or man-made, that is added to the basic H2O property of pure water. There is no such thing as "Pure Water" in the natural environment. Not all contaminants are bad or pose a health risk. Some contaminants may be desirable for taste or to balance the water in prevention of corrosion in household plumbing. Some contaminants may only be problematic when they exceed the EPA drinking water standards. Many contaminants can be extremely dangerous to health immediately or over the long term in even extremely small amounts.

The Environmental Protection Agency (EPA) sets Drinking Water Standards for protecting drinking water. These standards are made up of the National Primary Drinking Water Regulations and the National Secondary Drinking Water Regulations. The Primary Standards set levels of contaminants that may pose a health risk when present in drinking water supplies and are known or anticipated to occur in public water systems. The Secondary Standards are non enforceable guidelines that establish recommendations for contaminants that may cause cosmetic effects such as skin or tooth discoloration and aesthetic effects such as taste, odor and color. The EPA recommends Secondary Standards to water treatment systems but does not require systems to comply.

If you have a well system for your home, you are responsible for your water quality and assuring it is safe for you and your family. Generally, homeowners only test their well water after the well system is installed and may not do it again. This initial test is usually a requirement for the local board of health and may not check for all the EPA Safe Water Drinking Act standards. Failure to check your well water can be a dangerous gamble as ground and surface water is susceptible to contaminants at all times. Without a periodic comprehensive test of your drinking water, you may be putting yourself and your family at risk. Click here for more information on Well Water.

There are many factors that impact the quality of water that comes out of your household tap. The water treatment plant adds chemicals to the water through the process of treating the water, which may become contaminants with potential health risks. Some of these water treatment chemicals may not be eliminated and can be transported in the water to your home. Municipal water treatment plants can not remove every possible contaminant in water. The Safe Drinking Water Act (SDWA) sets legal limits for certain contaminants that consider human health and the ability of municipal water treatment systems to achieve these levels based on available technology. Considering the average person uses 100 gallons of water per day, there is a tremendous load on a municipal water treatment system to make that amount of water meet the SDWA standards. 90% of people that get their water from a community water system are serviced from a medium to very large system (serve 3,301 to 100,000 people). Your water treatment system may be responsible for delivering 330,100 to 10,000,000 gallons of drinking water per day. With this amount of drinking water demand, it may not be economically feasible for a municipal water treatment system to remove certain contaminants to a level that will have no health risk to humans.

Water that has been treated by a public or community treatment system has to be transported to your home and out of your faucet. Since water is a universal solvent, this distribution system can contribute contaminants to water from the composition of the piping, potential breaks in underground distribution lines and everything else the water may come in contact with before it leaves your faucet.

2006 EPA National Public Water System Annual Compliance Report

National Public Water System Compliance Summary
Type of Violation

Number of Systems with Violations

Number of Violations

Users Served

All Violation Types

42,108 128,666 81,466,047
Health-based 11,115 18,637 26,483,028
Monitoring & Reporting 29,660 91,077 49,152,615
Consumer Confidence Report (CCR) 7,333 11,346 17,838,339
Public Notification 7,606 7,606 7,266,860
  • 7% of America's public community water systems that serve 10% of all the public water system users reported a violation of a health-based drinking water standard.
  • 27% of the population served by public water systems received drinking water from a system that reported a violation of a health-based standard or was cited for a significant violation of a monitoring and reporting requirement or didn't issue a consumer confidence report and public notification, if required.
  • Of the 156,182 public water systems nationwide, the EPA determined that 14,036 (9%) systems were in significant non-compliance for calendar year 2006.
  • Click here to view EPA Water System Compliance Report.

How Water Can Become Contaminated

Water is a universal solvent, meaning it will pick up a bit of everything it touches. Contaminants may come from direct discharges as point sources of pollution or they may come from non-point sources such as surface runoff or contaminated groundwater. Natural sources and human actions can both contribute to water contamination. Residential, municipal, commercial, industrial and agricultural activities can all affect surface and groundwater quality. Here are some examples of potential sources of water contaminants:

Storage Tank Leakage - underground and above ground storage tanks are common for storing heating oil, gasoline, diesel fuel and industrial chemicals. Until the mid-1980's, most underground storage tanks were made of bare steel that would corrode and leak over time. The following statistics represent the state of underground storage tanks that are used to store petroleum and certain hazardous substances. According to the EPA as of September 30, 2005:

                  • Active Underground Storage Tanks - 653,621
                  • Confirmed Releases - 452,041
                  • Cleanups Completed - 332,799

Chemical Spills - tanker trucks and train cars carrying chemicals are another hazard. In 1990, the EPA indicated that 16,000 chemical spills from trucks, trains and storage tanks occur every year. Most often these spills occur when materials are being transferred.

Septic System Use - About 25% of all homes in the US utilize a septic system to dispose of human waste. Improperly sited, designed, constructed or maintained systems can contaminate groundwater with bacteria, viruses, nitrates, detergents, oils and chemicals. Dumping of toxic household chemicals down the drain also contributes to groundwater contamination through a septic system.

Naturally Occurring Substances - substances such as decaying organic matter, iron, manganese, chloride, fluoride, sulfates and radionuclides can become dissolved in water and move in streams and groundwater. They may become a health threat or create water quality problems when at undesirable levels.

Industrial Effluent - releases of toxic chemicals and manufacturing by-products into the environment can create water contamination. There is a vast amount and types of chemicals used for industrial purposes. Active and abandoned mines can be another source of groundwater contamination with the release of heavy metals and other undesirable substances.

Landfills - chemicals that should be disposed of in hazardous waste landfills, which have special protective barriers, sometimes will end up in municipal non-protected landfills. Newer landfills have collection systems with clay or synthetic liners to capture the contaminant liquid. Most older landfills do not have safeguards and may be built over aquifers with very permeable soil to increase the risk of leaching into the groundwater.

Sewer Distribution Piping - the distribution piping in a municipal sewer system carrying wastes away from a building can leak fluids into the surrounding soil and groundwater. This sewage can contain bacteria, heavy metals, organic matter, inorganic salts, viruses and nitrogen.

Drinking Water Distribution Piping - the water quality leaving a municipal treatment plant may be acceptable, but there are a variety of physical, chemical and biological factors that can affect the water quality before it enters your home. Drinking water being transported from a municipal treatment system may pick up contaminants from breaks in the piping that can allow outside contaminants inside. Contaminants can also be picked up from the distribution piping itself. Much of the nation's distribution piping is aging and in 2002, there were 200,000 water main breaks nationwide. For example, some older distribution systems may still have lead pipe used for the service line to the home or there may be asbestos from the asbestos-cement pipe lines. Steel and iron pipes can corrode and leach zinc and iron into the water. In a 2002 EPA report titled "Health Risks from Microbial Growth and Biofilms in Drinking Water Distribution Systems", the EPA stated that biofilms, which protect microbes (possible disease causing pathogens) from disinfection, are likely to be present in all distribution systems and that "biofilms can act as a slow-release mechanism for persistent contamination of the water."

Land Use - millions of tons of fertilizers, pesticides and herbicides are applied to the land annually for crop production, residential and business lawn care and facility maintenance. These toxic substances can easily enter the ground or become part of surface runoff into other water bodies to contaminate surface and groundwater. In the EPA National Pesticide Survey conducted between 1985 and 1992 on 1,300 public drinking water wells, it was concluded that a significant percentage of wells contained pesticides at concentrations exceeding the Federal Maximum Contaminant Level (MCL) and almost 4% of the wells had nitrate concentrations above the MCL. In 1990, the EPA noted that more than 11 million tons of salt is applied annually to roads for ice removal. Precipitation can carry the salt into groundwater to create undesirable elevated levels. Storm water drains can also carry contaminants into the groundwater.

Common Water Quality Contaminants

There are many possible contaminants that may pollute your water from various sources. Here are a few of the most common water problems and water pollutants that may be present in your tap water. Some of these water problems and pollutants may be in your tap water even if the water treatment plant has met all of the Safe Drinking Water Act standards due to the distribution of water from the treatment plant through the household piping.

There are thousands of chemicals present in our environment with new ones being added everyday. It would be impossible to test for the presence of each chemical in our water or to fully understand the health consequences of each one. To further complicate this serious situation, various chemicals can form new, more toxic products when they come in contact and react with each other. You must take a pro-active stand and assure yourself that you are providing the safest drinking water for you and your family

Acrylamide -This organic chemical is used in the water treatment process. There are currently no acceptable means of detecting acrylamide in drinking water. The EPA has established that no amount of this chemical should be present in water. Short term exposure can cause damage to the nervous system. Long term exposure can lead to paralysis and cancer.

Arsenic -A natural and man made ground water contaminant, this contaminant can cause skin damage, circulatory system problems and an increased risk of cancer.

Asbestos - This is a fibrous mineral that can contaminate water naturally through movement in the ground or through contact with water pipes that have used asbestos as part of its composition such as in concrete water distribution pipes. Asbestos increases the risk of developing benign intestinal polyps.

Biological Pathogens - These are a variety of waterborne pathogens that can cause disease and include Coliform Bacteria like E coli, Viruses like influenza, and Cysts like Cryptosporidium and Giardia. This group of contaminants can cause gastroenteric disease such as Giardiasis, or other symptoms and unpleasant intestinal disorders such as diarrhea, cramps, nausea and headaches. Biological pathogens are a major health threat for people with weakened Immune systems.

Copper -This metal is widely used in household plumbing materials and corrosion of household copper piping may lead to excessive levels in drinking water. Copper is an essential nutrient but excessive amounts can cause stomach and intestinal distress, liver and kidney damage and anemia.

Cryptosporidium - A microbial pathogen that is highly resistant to traditional disinfection practices used by municipal water treatment operations. Current EPA drinking water standards are not designed to assure elimination of this parasite. Exposure can cause gastrointestinal illness and individuals with weakened immune systems can experience more severe effects, including death.

Disinfection and By-Products - Water is disinfected before it enters the distribution system to help control dangerous microbes. Contaminants are formed when these disinfectants (usually chlorine, chloramines or chlorine dioxide) react with organic matter that is present in the treated water, producing by-products such as trihalomethanes (THM's). Long-term exposure to some disinfection chemicals, such as chlorine and by-products may increase the risk of cancer and liver, kidney and central nervous system problems.

Epichlorohydrin - This is another organic chemical used in the water treatment process. It also can not be detected in drinking water. The EPA has established that no amount of this chemical should be present in water. Short term exposure can cause skin irritation, liver, kidney and nervous system damage. Long term exposure can lead to chromosome aberrations, adverse changes in the blood and cancer.

Heavy Metals - This classification of contaminants include metals such as Mercury, Zinc, Copper, Cadmium and Lead and usually enter the water supply as industrial waste or through plumbing systems. Excessive amounts can lead to kidney and liver damage, central nervous system damage and gastrointestinal distress.

MTBE - Methyl Tertiary Butyl Ether is a gasoline additive used since 1979. Contamination of groundwater primarily occurs from leaking fuel storage tanks. MTBE dissolves easily in water and does not "cling" to soil very well, it migrates faster and farther in the ground than other gasoline components, thus making it more likely to contaminate public water systems and private drinking water wells. MTBE does not degrade easily and is pesistent in the environment. The EPA has not set a standard for MTBE as the health effects of ingestion at low concentrations are still unknown, but has placed MTBE on the Contaminant Candidate List for continued study. Water will taste and smell like Turpentine at levels around 20-40 parts per billion (ppb).

Lead - Prior to 1930, lead piping in homes was common practice. Lead-free solder used for connecting copper piping was a requirement only after 1988 and even today, pipes fittings and devices (except those that dispense water for ingestion) can contain up to 8% lead and still be considered "lead free". Short term effects of excessive lead includes interference with red blood cell chemistry, delays in physical and mental development in babies and young children. Long term effects include stroke, kidney disease and cancer.

Nitrates - The use of nitrogen based lawn, garden and farm fertilizers leach nitrates into the soil and find their way into our ground and surface drinking water. When Nitrates are ingested it is converted to Nitrites which combine with the blood's hemoglobin and prevent oxygen from being carried to the tissues of the body. A serious health threat in infants.

Radon and Radium - Certain minerals are radioactive and may emit a form of radiation known as alpha radiation. Radon gas can dissolve and accumulate in underground water sources, such as wells. 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. Approximately 5% of a homes Radon level is linked to the water supply. Naturally occurring radioactive elements enter the water and are either inhaled or ingested causing an increase risk of cancer.

Sediments - Primarily an aesthetic concern, sediments are solid particles in water and can be derived from a variety substances.

Taste, Odor and Color - Water can have objectionable tastes and odors which may make it undesirable to drink. The cause may be from chemicals added to the water such as chlorine used in the disinfection process, from a high mineral concentration, from hydrogen sulfide gas that produces the "rotten egg odor" or the presence of organic matter. Discoloration can be caused by microscopic suspended particles, Humeric Acids or excessive iron

Turbidity - Turbidity is cloudy water caused by the abundance of very tiny solid or dissolved particles in the water. The composition of the particles may be inorganic minerals or organic matter. This problem is most common with water derived from lakes, streams or ponds. Although Turbidity may not be a health risk by itself, high levels may interfere with proper disinfection, provide a medium for microbial growth and indicate the presence of microbes.

Volatile Organic Chemicals (V.O.C's) - These are a class of chemicals that are very pervasive in our society through the use of solvents, gasoline, petrochemicals and cleaners as well as numerous manufacturing processes and leaking storage tanks. Over 2,000 organic chemicals have been identified in drinking water. Ingestion of these contaminants can increase cancer risk and produce anemia, nervous system and circulatory problems and organ damage.