Environmental Health Fact Sheets

Abandoned Wells

An estimated 400,000 private water wells in Illinois provide drinking water to approximately 1.3 million people. Each year, many of these wells are abandoned when they are replaced with new wells or when homes are connected to community water systems. A large number of these abandoned wells are large diameter dug wells constructed with brick or stone casings, and range in depth from 20 to 50 feet. An abandoned well can pose a health and safety hazard if it is improperly sealed or not sealed a...read more

Alachlor and Atrazine in Groundwater

Alachlor and atrazine are used as selective herbicides for controlling grasses and broadleaf weeds. Exposure to alachlor and atrazine in groundwater occurs mainly by drinking contaminated water. Alachlor can cause skin or eye irritation. Drinking water that contains alachlor for long periods may damage the liver, kidneys, eyes and spleen. Atrazine can cause skin and eye irritation, as well as skin allergies. Drinking water that contains atrazine for long periods may damage the heart and liver...read more

Arsenic in Groundwater

Arsenic is a metal-like substance found in small amounts in nature. Elevated levels of arsenic can be found naturally in groundwater in some areas of Illinois. Arsenic in groundwater may also be the result of contamination caused by hazardous waste or industries that use arsenic. Drinking water containing high levels of arsenic may cause health problems.

Bored Wells

A Safe Water Supply Depends on Location and Construction

Water wells must be located and constructed to provide safe water at all times and under all conditions.

Bacterial contamination of a water supply generally occurs when seepage from sewage systems or surface water enters the well. Contamination may enter the well through the top or by seeping through the well walls. Tests have shown that bacterial contamination is usually eliminated after water has filtered through 10 fe...read more

Commonly Found Substances in Drinking Water and Available Treatment

Some common constituents of drinking water include hardness, sulfates, iron, chlorides, pH (acidity and alkalinity), total dissolved solids and hydrogen sulfide.

Drilled Wells

A Safe Water Supply Depends on Location and Construction

Water wells must be located and constructed to provide safe water at all times and under all conditions.

Bacterial contamination of a water supply generally occurs when seepage from sewage systems or surface water enters the well. Contamination may enter the well through the top or by seeping through the well walls. Tests have shown that bacterial contamination is usually eliminated after water has filtered through 10 fe...read more

Driven Wells

A Safe Water Supply Depends on Location and Construction

Water wells must be properly located and constructed to provide safe water at all times and under all conditions. 

Driven wells can also be referred to as sand-point wells.

Emergency Hauling, Storing and Disinfecting of Water Supplies

Areas of Illinois can experience conditions that require the purchasing and hauling of drinking water by home owners, farmers, institutions and small private subdivisions whose own water supplies are not adequate. The information on emergency water supply and treatment is used by owners of such supplies until the temporary water shortages are over.

Iron in Drinking Water

Iron can be a troublesome chemical in water supplies. Making up at least 5 percent of the earth’s crust, iron is one of the earth’s most plentiful resources. Rainwater as it infiltrates the soil and underlying geologic formations dissolves iron, causing it to seep into aquifers that serve as sources of groundwater for wells. Although present in drinking water, iron is seldom found at concentrations greater than 10 milligrams per liter (mg/L) or 10 parts per million. However, as little as 0.3 ...read more

Methane in Groundwater

Methane (CH4) is a colorless, odorless, flammable gas used as a fuel to heat homes. Methane is produced in nature by the decay of organic matter and the digestion process of various organisms. Elevated levels of methane can be found naturally in groundwater in some areas of Illinois. Methane in groundwater also may be the result of contamination caused by leaks from underground methane storage fields or landfills. Elevated levels of methane released into a building may lower oxygen...read more

Nitrates in Drinking Water

Nitrate (NO3) is a compound of nitrogen and oxygen found in nature and in many food items in our diet. Generally, the concentration of nitrates in the ground water is low. The main adult human intake of nitrates is from food rather than from water. Vegetables such as spinach, lettuce, beets and carrots contain significant amounts of nitrate. Drinking water normally contributes only a small percentage of our total nitrate intake.

High nitrate levels in drinking water pose a h...read more

PFAS in Drinking Water

Per- and polyfluoroalkyl substances (PFAS) are chemicals produced in the United States since the 1940s. They are used for applications ranging from firefighting to stain and waterproofing of consumer products, such as carpet, clothing, and food packaging. Some PFAS are no longer made due to environmental and human health concerns, but they persist in the environment and may contaminate surface waters and groundwaters near sites where they were made or used. Newer PFAS continue to be produced ...read more

Radium in Groundwater

Radium (Ra) is a naturally-occurring radioactive element that can be present in rocks and soil in the earth’s crust. Small amounts of radium can also be found in groundwater supplies. Radium can be present in different forms, called isotopes. The most common isotopes in Illinois groundwater are Ra-226 and Ra-228. The main type of radiation emitted by radium is an alpha particle.

Vinyl Chloride in Groundwater

Vinyl chloride is a colorless gas that, at high levels, has a mild, sweet odor. Breathing high levels of vinyl chloride (approximately 10,000,000 ppb) can make you feel dizzy or sleepy. Breathing very high levels of vinyl chloride over several years may cause immune disorders and damage to the liver, kidneys and nerves.

Well Sampling for Coliform & Nitrate

Bacteria and parasites that cause illness can enter a well in many ways. Whether the contamination comes from the materials and tools used in the well’s construction, from septic failures near the well or from feedlot runoff, the bacteria and parasites must be destroyed to ensure safe water. Testing for coliform bacteria will reveal whether your water supply may be contaminated with infectious organisms, but it will not provide a direct measure of pathogenic, or disease-causing, bacteria. A n...read more