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University of Nebraska–Lincoln

UNL Water

Your natural resource for reliable drinking water information

girl gettting a drink from faucetDrinking Water Quality

You expect drinking water to be safe. However, contaminants such as gases, minerals, bacteria, metals, and other chemicals suspended or dissolved in the water can affect your health and influence the quality of your water. The U.S. Environmental Protection Agency (EPA) has established limits, or standards, on the concentration of certain drinking water contaminants allowed in public water supplies. These limits are set to protect your health and ensure that your public water supply is of good quality.

The EPA standards for drinking water fall into different categories including:

Primary Standards:

  • Based on health considerations.
  • Protects against pathogens, radioactive elements, and toxic chemicals.
  • Maximum Contaminant Level (MCL) is the highest allowable concentration of a contaminant allowed in public drinking water.
  • MCL is enforced.

Secondary Standards:

  • Based on offensive taste, color, odor, corrosivity, foaming and staining properties.
  • Manages aesthetics.
  • Secondary Maximum Contaminant Level (SMCL) is the guideline for public water treatment plant operators attempting to provide the best quality water possible.
  • SMCL is not enforced.                                   

Action Level:

  • Based on health considerations.
  • The concentration of a contaminant in water, which if exceeded in a specified percentage of water samples tested, triggers actions that a public water system must follow. Required actions may include: additional monitoring, treatment, public notification, and other actions.
  • Enforced.

Health Advisories:

  • Based on health considerations.
  • Estimates of acceptable levels for a chemical substance in drinking water over a given period of time based on currently available information on its health effects.
  • Not enforceable.

The EPA National Drinking Water Regulations, includes a list of regulated contaminants and their MCLs. 

No EPA drinking water standards have been established for pharmaceuticals and endocrine disrupting chemicals* in public drinking water supplies. Research is not conclusive on potential human health effects from trace amounts of these products in water supplies.

The EPA is taking several actions to increase the understanding of potential risks and best disposal practices. Actions include:

  • collecting information from hospitals, long-term care facilities, and hospices on current disposal practices;
  • commissioning the National Academy of Sciences to provide scientific advice on potential risk to human health;
  • expanding a fish tissue study;
  • developing a methodology to establish water quality criteria to protect aquatic life; and,
  • conducting studies on occurrence of these products in sewage sludge and wastewater.
  • In addition, EPA is participating with the World Health Organization to study risk assessment methods for pharmaceuticals.

 

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Information presented within the drinking water section of this Water Web site has been reviewed by University of Nebraska - Lincoln Drinking Water Team members Bruce Dvorak, Sharon Skipton, Wayne Woldt, David Shelton, and Jan Hygnstrom.
Additional Resources

UNL Extension Publications

References* on various minerals and contaminants in drinking water including sources, health effects, testing and management options:

Drinking Water: Bottled or Tap?* Provides in depth discussion of the regulation and safety of drinking water from various sources, both public and private.


*Documents are in PDF format. Download the current version of Adobe Reader

Private Wells

Quality of Private Drinking Water Supplies

The quality of private water supplies is not regulated in Nebraska by federal or state mandates.  Counties or cities may regulate the quality of private water supplies.  Therefore, the quality of private drinking water supplies in Nebraska is at the discretion of the water user except in counties or cities where local regulations exist.

EPA drinking water standards for public water supplies can serve as voluntary guidelines for private system users.  Users can compare their water test results with the EPA standards to assess the quality and risk associated with their water supply.