Common Contaminants

Coliform bacteria are a group of several bacterial species that live naturally in the intestinal tracts of humans and animals. Some types of coliform bacteria also live naturally in soil and surface water. Coliform bacteria are used as a standard for bacterial quality in drinking water, as their presence in groundwater indicates sewage or surface water is entering and contaminating the water supply. Bacteria are common in the environment and generally are not harmful; however, some types can cause serious illness. Moreover, it is likely other harmful germs are present if the result is positive.

Additional information is available on the web:

• IDPH's fact sheet, Well Sampling for Coliform and Nitrate
• U.S. EPA's web page, E. Coli 0157:H7 in drinking water – U.S. EPA
• Water Systems Council fact sheet, Wellcare® information sheets

This pollutant may be found at elevated levels due to nearby septic systems, manure storage areas, feedlots or farm fields. Wells vulnerable to nitrate contamination include shallow sand point wells and large diameter dug or bored wells, and wells with damaged, leaking casing or fittings. It is especially important that mothers-to-be and infants less than 6 months old are cautious about their drinking and cooking water because too much nitrate in drinking water can cause blue baby syndrome in infants, which is a result of the blood not being able to transport oxygen, causing asphyxiation. Although nitrate occurs naturally in soil and water and low levels are not toxic, nitrate can be harmful especially to babies when water levels are greater than 10 milligrams per liter. Testing for nitrate should be done at least once a year or more often if an infant or a pregnant woman is in the household. Nitrate levels may indicate that your well is vulnerable to other contaminants, including pesticides.

The following web sites contain additional information:

• IDPH fact sheet, Nitrates in Drinking Water
• Water Systems Council fact sheet, Wellcare® information sheets

These manufactured chemicals do not occur naturally, and are widely used on farmland throughout Illinois. The majority of SOCs are made up of pesticides, herbicides and insecticides, while others are used as plasticizers, wood preservatives, flame retardants, and solvents, and produced as by-products or waste materials. Some man-made chemicals are undetectable through sight and smell; however, certain aromatic chemicals, such as those in coal tar, have a very noticeable odor. Testing your drinking water is the only way to know for sure if your water is safe, especially if you live near farmland where pesticides are applied. Being aware of any farming activities that occur near your well, such as learning the specific chemicals being used, can narrow the range of chemicals to be tested.

More information is available on the web at the following sites:

• Alachlor and atrazine are two herbicides that are widely used on corn and soybean fields for controlling grasses and broadleaf weeds. IDPH offers an online fact sheet, Alachlor and Atrazine in Groundwater
• University of Illinois at Urbana-Champaign Cooperative Extension Service fact sheet, Pesticides and Groundwater: Pesticides as Potential Pollutants
• The following report and contaminant specific fact sheets provide more detailed information regarding man-made chemicals and pesticides:
  • Natural Resources Cornell Cooperative Extension's Pesticides: Health Effects in Drinking Water

VOCs are man-made substances that tend to evaporate or break down easily in surface water, but they can persist for many years in groundwater and can travel long distances from where they were spilled or dumped. They also can have a variety of potential health effects. These chemicals are commonly used as solvents, degreasers, dry-cleaning chemicals, and as octane enhancers in gasoline. Although these substances evaporate readily, they can enter the body through ingestion, inhalation and skin absorption as well as ingestion. Some VOCs have a chemical, fuel or fruity odor and may taste bitter, but many man-made chemicals can go unnoticed. Most VOCs do not have any detectable taste or smell; therefore testing is the only way of knowing for sure if they are present in your drinking water. Please note: if you are collecting your own sample for a VOC test, it is imperative to remove the faucet aerator prior to collecting your sample. See the general procedures for collecting water samples for VOC testing fact sheet for more information. ( Procedimiento general para recoger muestras de agua para hacerles la prueba de químicos orgánicos volátiles)

• IDPH's fact sheet, Vinyl Chloride In Groundwater
• Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs provides information for volatile organic chemicals such as benzene, trichloroethylene (TCE), tetrachloroethylene (PCE) and vinyl chloride, as well as metals such as cadmium, lead and arsenic.
• Water Systems Council fact sheet, Wellcare® information sheets
• University of Wisconsin–Extension, Drinking Water and MTBE: A Guide for Private Well Owners (6 pages, pdf)

• The U.S. Department of the Interior, U.S. Geological Survey's report, A National Survey of Methyl tert-Butyl Ether and Other Volatile Organic Compounds in Drinking-Water Sources: Results of the Random Survey (94 pages 2003.)
• The Pennsylvania Department of Environmental Protection's online publication, Citizen's Guide to Volatile Synthetic Organic Chemicals in Drinking Water gives you everything you ever wanted to know about VOCs. Open the publications folder and then the water standards folder and then click on drinking water.

The following list contains VOCs that are commonly tested for by public water supplies and can be used as a guide for testing private well water in Illinois. Please note that this list provides general guidance and is not meant to be an all inclusive parameter list.