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Drinking Water

Drinking Water

Drinking water can become contaminated through natural and human activity. Contaminated drinking water can cause health problems. Factors such as how much of a  contaminant a person contacts (the dose), how long they are in contact with it (the duration) and a person’s sensitivity (e.g. overall health, genetics, age) help determine whether contact with any contaminant could affect health.

Many contaminants are found at very low levels that are not expected to cause health problems, while higher levels may require action to reduce exposure.

Visit the MDHHS webpage, Care for MI Drinking Water, to learn how different contaminants can get into your drinking water and how to maintain your home’s water quality. The MDHHS webpage, Get Ahead of Lead, offers recommendations for protecting against exposure to lead in drinking water and the MDHHS webpage about water filters can help you make the best choice for your home.

Running kitchen faucet
Flooded roadway with a climate change icon in the upper right corner of the image

Climate Change and Drinking Water

Flooding can strain municipal water infrastructure and private residential wells.

Floodwaters can contain pollutants that contaminate private wells and overwhelm water treatment plants, potentially affecting their ability to process drinking water.

The following factors can increase flooding:

  • Rain, snow, sleet and hail that occur more often and are more severe.
  • When and how quickly snow melts.
  • Early spring rainfall.

Check out our Flood Safety Series to learn more about what you can do to prepare for floods and how to stay safe during and after a flood event.

Some environmental chemicals can enter home drinking water. This can happen in homes connected to municipal systems when plumbing fixtures or other local factors affect water quality. However, municipal water supplies are regularly tested to meet federal and state drinking water standards. Because of this monitoring and testing, contaminated drinking water is more often a concern for private well users than for municipal water customers. Municipal customers can learn about their water quality through their local water utility’s Consumer Confidence Report.

If you want to learn more about  contaminants that might be in drinking water, the resources below can help. Many of these resources also include steps you can take to lower your exposure to these possible hazards.

Not all contaminants that may be found in a home are listed here. If you are interested in understanding health effects associated with a  contaminant that is not listed here, call your healthcare provider or our Environmental Health Hotline at 800-648-6942, Monday through Friday between 8 a.m. and 5 p.m. If you believe you are in immediate danger, call 911 or contact Poison Control at 800-222-1222.

Common acronyms on these pages include:

  • ATSDR – Agency for Toxic Substances and Disease Registry.
  • CDC – Centers for Disease Control and Prevention.
  • EGLE – Michigan Department of Environment, Great Lakes, and Energy.
  • EPA – United States Environmental Protection Agency.
  • FDA – Food and Drug Administration.
  • LEO – Michigan Department of Labor and Economic Opportunity.
  • MDHHS – Michigan Department of Health and Human Services.

Home Drinking Water: Potential Hazards

  • Coliform Bacteria

    How they may enter drinking water:  Coliform bacteria are commonly found in soil, lakes, rivers, on plants and in the intestines of mammals, including humans. Most coliform bacteria are not harmful themselves, but their presence in drinking water can indicate that the water system is vulnerable to contamination. One specific type, Escherichia coli (E. coli), can be harmful and is a strong indicator that fecal waste has entered the water. To learn more about where E. coli comes from, how to prevent contamination and when to test a residential drinking water well, see the factsheet Coliform Bacteria in Drinking Water (Spanish, Arabic).

  • Metals

    How they may enter drinking water: Many of the metals listed below occur naturally in soil and rock. While they are usually present at low levels, concentrations can be higher near industrial sites, landfills or other sources of contamination. Metals from these sources can sometimes migrate into groundwater or surface water that supplies drinking water. Municipal water systems routinely test and treat water for metals, but private well users are responsible for testing their own water and may not do so regularly. Metals can also enter drinking water from plumbing materials inside the home. Regardless of the source, once metals are present in drinking water, people may be exposed to levels that could pose health risks.

    • Aluminum: Aluminum is a naturally occurring element found in food, water, air and soil. Aluminum is also present in the environment due to some industrial activities. Once in the environment, it may be able to reach groundwater or surface water. To learn more, review these Frequently Asked Questions About Aluminum (Spanish, Arabic).
    • Arsenic: Michigan has naturally higher arsenic levels in groundwater compared to some other places in the country. Industrial activities, like pesticide and wood preservative production, may release high levels of arsenic into the environment. Once in the environment, it may be able to reach groundwater or surface water. Learn more at the MDHHS webpage on Arsenic in drinking water. Contact your local health department to find out more about naturally occurring groundwater arsenic levels in your area.
    • Cadmium: If industrial or agricultural contamination containing cadmium impacts soil or groundwater, it may migrate into drinking water. Cadmium may also be present in some older galvanized pipes, solder or fixtures, which could lead to drinking water contamination. To learn more, review these Frequently Asked Questions About Cadmium (Spanish, Arabic).
    • Chromium: Chromium is a naturally occurring element found in rocks, soil, water, plants and animals. Industrial activities may also  release chromium into the lakes, rivers or groundwater that become your drinking water. Chromium exists in several forms. One form, chromium VI (also called hexavalent chromium or Chromium 6) is of particular concern because of its harmful human health effects. Chromium VI may also get into drinking water from plumbing made with chromium-containing components link pipes, fittings, fixtures and faucets. To learn more, review these Frequently Asked Questions About Chromium (Spanish, Arabic).
    • Copper: While copper can be found naturally in drinking water, it often comes from a home’s pipes or faucets. Sometimes pipes corrode and then copper comes off the pipes and gets into your drinking water. Learn more at the MDHHS webpage on drinking water contamination.
    • Iron: Iron is a naturally occurring metal in soil and rocks and some areas in Michigan have naturally high levels of iron in groundwater. Iron may also get into drinking water from plumbing made with iron, like pipes, fittings, fixtures and faucets. Learn more at the MDHHS webpage on drinking water contamination.
    • Lead: The most common source of lead in drinking water is plumbing made with lead, e.g., pipes, fittings, fixtures and faucets. Lead can get into your drinking water when plumbing containing lead begins to break down or dissolve. Other ways lead can get into drinking water are through service lines or galvanized plumbing and parts of a well system. Learn more at the MDHHS webpage on drinking water contamination.
    • Manganese: Manganese is a naturally occurring element found in rocks, soil, water, plants, and animals. It often gets into private well water as groundwater moves through soil and rock that contain manganese. Human activities—such as steel production, mining, and other industrial processes—can also release manganese into the environment, where it may reach groundwater or surface water. Learn more at the MDHHS webpage on drinking water contamination.
    • Selenium: A small amount of selenium is an essential nutrient as part of a balanced diet, but too much can result in health problems. Selenium can enter the environment, including into drinking water sources, from mining operations and industrial activity such as the production of paints and metalworking. To learn more, review these Frequently Asked Questions About Selenium (Spanish, Arabic).

  • Nitrate and Nitrite

    How they may enter drinking water: Nitrates and nitrites can enter private wells when groundwater becomes contaminated. The most common sources are fertilizers, livestock waste and failing septic systems, which can seep into the soil and reach groundwater. In the environment, bacteria can convert nitrate into nitrite, a related compound that can also be harmful to health. Learn more at the MDHHS webpage on drinking water contamination.

    Since the 1950s, the Upper Midwest has experienced more frequent and more intense extreme precipitation events. The Fifth National Climate Assessment reports that households in the Midwest that rely on private wells may face a higher risk of nitrate contamination during periods of heavy rainfall and flooding.

  • PFAS

    How they may enter drinking water: Per‑ and polyfluoroalkyl substances (PFAS) are a large group of human‑made chemicals that do not occur naturally and break down very slowly in the environment. They have been used in many consumer products and industrial processes. When PFAS are released into the environment, they can move through soil and may reach groundwater or surface water that some people use for drinking. Learn more at the MDHHS webpage on PFAS in Drinking Water and at the following links:

  • Volatile Organic Compounds (VOCs)

    How they may enter drinking water: VOCs are a large group of chemicals that easily evaporate into the air (this is what ‘volatile’ means and more information about VOCs in indoor air is found here). VOCs can get into drinking water sources when products containing VOCs are used or spilled onto the ground.

    Some examples of products that contain VOCs are:

    • Products used in cleaning, degreasing and dry cleaning.
    • Fuels like gasoline and heating oil.
    • Chemicals used in plastics, paints and adhesives

    Learn more at the MDHHS webpage on drinking water contamination and learn more about common VOCs from the following factsheets:

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