Communicating Results

Roughly two-thirds of Wisconsinites rely on groundwater for their drinking water.

Understand what makes a well vulnerable, susceptible contaminants, and the health risks associated with drinking water exceeding state standards. Work together with county public health departments to provide support to communities vulnerable to well contamination.

Well Construction Matters

Visit this EPA website that describes the types of wells, components of well construction, and how construction can contribute contamination vulnerability.

Learn More

Common contaminants associated with land use


The groundwater standards for nitrate were adopted in Cycle 5 (1994).

  • Enforcement standard = 10 mg/L (as nitrate-nitrogen)*
  • Preventive action limit = 2 mg/L (as nitrate-nitrogen)*

Nitrate overview

Nitrate in Drinking Water handout

Nitrate in Private Well Water factsheet


Bacteria (Escherichia coli)

The groundwater standards for Escherichia coli (E.coli) were recommended in Cycle 10 (2019). The rule to adopt these standards was approved by the Governor on February 2, 2023.

  • Recommended enforcement standard = 0 CFU
  • Recommended preventive action limit = 0 CFU

Bacteria (total coliform)

The groundwater standards for bacteria (total coliform) was first adopted in Cycle 1 (1985), updated in Cycle 6 (1995), and reviewed as part of Cycle 10 (2019).

  • Enforcement standard = 0 CFU
  • Preventive action limit = 0 CFU

Bacteria overview

Bacteria in Private Well Water factsheet


The groundwater standards for atrazine were adopted in Cycle 2 (1988) and updated in Cycle 4 (1992).

  • Enforcement standard = 3 µg/L*
  • Preventive action limit = 0.3 µg/L*

Atrazine overview

Atrazine in Private Well Water factsheet

How are standards determined?

Health and environmental impacts are considered when setting water quality standards. When public health can be impacted, the Department of Health Services (DHS) contributes expertise to support the Department of Natural Resources (DNR) set regulatory standards. State agencies must also comply with federal standards enforced through the Environmental Protection Agency (EPA).

Interpret Well Water Quality Results

Use this UWSP Water and Environmental Analysis Lab interactive tool to help interpret results from common well sampling packages.

Launch Tool