Madison – Wisconsin
Madison Water Utility is a public water system owned and operated by the City of Madison, serving over 250,000 residents across Madison and surrounding areas. The utility manages an extensive infrastructure consisting of 20 active wells, 33 reservoirs (including seven elevated water towers), and over 900 miles of interconnected water transmission and distribution mains. Funded by water rates rather than taxes, the utility operates under the governance of the Water Utility Board and the Madison Common Council.
Madison draws its drinking water exclusively from a deep sandstone aquifer beneath the city, which is naturally replenished by rain and snowmelt filtering through soil and rock. The city’s wells reach 500-1,100 feet deep into this aquifer, collectively pumping approximately 10 billion gallons of water annually. This groundwater source naturally contains minerals such as iron and manganese, which, while not health concerns, can affect water color and taste. To address these aesthetic issues and emerging contaminant concerns, the utility has been systematically upgrading infrastructure, adding filtration systems at key wells, and conducting regular monitoring to ensure water quality exceeds regulatory standards.
Madison Water Quality: Current Status (2024-2025)
Latest Testing Results
- PFAS Status: Low levels of PFAS have been detected in Madison’s wells, but all active wells comply with both Wisconsin’s current standard (70 parts per trillion) and the stricter federal guidelines established by the EPA in March 2023.
- Well 15 Treatment: Well 15 on Madison’s east side has been offline since 2019 due to PFAS concerns. A $5.9 million treatment facility using granular activated carbon and ion exchange resin is under construction, with completion expected in summer 2025.
- Chromium-6 Levels: Low levels (less than 2 parts per billion) have been detected in 14 of Madison’s 22 wells, well below California’s regulatory standard of 10 parts per billion. Currently, there is no federal standard for chromium-6.
Aquifer Water Source
- Deep Sandstone Aquifer: Madison’s water comes from a natural underground reservoir consisting of saturated sandstone hundreds of feet below the city, naturally filtered through layers of soil and rock.
- Well Depths: The city’s municipal wells reach 500-1,100 feet deep into the aquifer, drawing from specific zones to maintain water quality and supply reliability.
- Natural Minerals: The sandstone aquifer naturally contains iron and manganese, which, while not health concerns, can affect water aesthetics and require special treatment at several well facilities.
Treatment Approaches
- Targeted Filtration: Madison is systematically adding iron and manganese filtration systems to wells with elevated levels of these minerals, improving water taste, odor, and appearance.
- Chlorine Disinfection: Small amounts of chlorine are added to destroy harmful waterborne viruses, bacteria, and microbes, ensuring microbiological safety.
- Fluoridation: Madison has added fluoride to its water since 1948 at the direction of the Common Council to reduce the risk of dental cavities, following recommendations from Public Health Madison Dane County.
Infrastructure Upgrades
- Aging Infrastructure: Madison is undertaking a 30-year plan to replace approximately 300 miles of aging water mains with modern cement-lined ductile iron pipe wrapped with protective plastic sheeting.
- Well Facility Modernization: Several well facilities are being upgraded or rebuilt to address aging infrastructure, improve reliability, and add filtration capabilities.
- Advanced Treatment: Specialized treatment systems for specific contaminants are being added where needed, such as the PFAS treatment system at Well 15.
Water Quality Monitoring
Madison Water Utility takes water quality extremely seriously, routinely collecting more samples and conducting more tests than required by the EPA and Wisconsin DNR. The utility performs thousands of tests annually to monitor for regulated contaminants and emerging concerns. Regular testing for PFAS is conducted at all wells, with results published on the utility’s website and in annual Water Quality Reports. The city also conducts main flushing operations in spring and summer to remove naturally occurring iron and manganese sediment from the distribution system. This proactive approach to water quality management, combined with strategic infrastructure investments, ensures that Madison’s drinking water consistently meets or exceeds all federal and state safety standards while addressing aesthetic concerns.
Recommendations for Madison Residents
Check Your Water Source
Visit the Madison Water Utility website (cityofmadison.com/water) and enter your address to find out which well serves your home. This information can help you understand specific water quality characteristics in your neighborhood and stay informed about any maintenance or upgrades.
Consider Home Filtration
If you’re concerned about specific contaminants or aesthetics, consider a NSF-certified filter designed for your needs. For PFAS reduction, look for filters using activated carbon or reverse osmosis technology. For iron and manganese (which cause discoloration), whole-house filters can be effective.
Address Discolored Water
If your water becomes discolored (usually from iron and manganese sediment), run a cold water tap at full force from the lowest level of your home (like a basement sink) until the water clears, typically within 15 minutes. If it doesn’t clear, call Madison Water Utility at (608) 266-4661.
Stay Informed
Review Madison Water Utility’s Annual Drinking Water Quality Report, which provides comprehensive testing results and explains water treatment processes. Follow the utility on social media and sign up for email updates about water quality issues, main flushing schedules, and infrastructure projects.
Report Water Concerns
Contact Madison Water Utility’s Water Quality Department at (608) 266-4654 with questions or concerns about your water quality. For water main breaks, service emergencies, or other urgent issues, call the utility’s 24-hour dispatch line at (608) 266-4661.
Frequently Asked Questions
Is Madison’s tap water safe to drink?
Yes, Madison’s tap water meets all federal and state drinking water standards and is considered safe to drink. The Water Utility conducts thousands of tests annually, more than required by regulatory agencies, to ensure water quality.
Madison Water Utility has been proactive in addressing emerging contaminants like PFAS, with all active wells testing below both Wisconsin and federal standards. The utility also implements comprehensive monitoring for naturally occurring minerals, disinfection byproducts, and other potential contaminants. Aesthetic concerns like discoloration from iron and manganese are being addressed through filtration system upgrades at several wells, though these minerals do not pose health risks.
What is being done about PFAS in Madison’s water?
Madison Water Utility has taken a comprehensive approach to addressing PFAS concerns:
1. Regular Testing: All wells are tested for PFAS compounds, with results published transparently on the utility’s website
2. Well 15 Treatment: Well 15, which had elevated PFAS levels, was taken offline in 2019 and will remain so until construction of a $5.9 million treatment facility is completed in 2025
3. Advanced Technology: The Well 15 treatment facility will use a hybrid approach combining granular activated carbon and ion exchange resin to remove PFAS to non-detectable levels
4. Federal Funding: The project secured funding through the Safe Drinking Water Loan Program made possible by the Bipartisan Infrastructure Law, with about half as a grant
Madison’s proactive approach has positioned it ahead of EPA regulatory requirements that will take effect in 2027.
Why does my water sometimes look discolored?
Discolored water in Madison is primarily caused by naturally occurring iron and manganese sediment from the sandstone aquifer. Several factors can stir up this sediment:
• Main flushing: The utility regularly flushes water mains in spring and summer to remove accumulated sediment
• Pressure changes: Water main breaks, repairs, or nearby construction can cause pressure changes that disturb sediment
• Fire hydrant use: Fire suppression activities or hydrant testing can stir up sediment
• Changes in flow direction: Adjustments to the distribution system can change water flow patterns
While discolored water is not harmful, it can be unappealing and may stain laundry. The Water Utility is addressing this issue by installing iron and manganese filtration at selected wells, and residents can clear discolored water by running a cold water tap at full force until the water clears.
How is Madison addressing its aging water infrastructure?
Madison is undertaking a comprehensive approach to upgrading its water infrastructure:
Pipeline Replacement:
• The utility is implementing a 30-year plan to replace approximately 300 miles of aging water mains
• Modern cement-lined ductile iron pipe wrapped with protective plastic sheeting is being installed, with an expected lifespan of 100+ years
• Where feasible, trenchless technologies are used to create new pipes within existing ones
Well Facility Modernization:
• Several well facilities are being rebuilt with enhanced treatment capabilities
• Increased reservoir capacity for better fire protection and emergency supply
• Addition of filtration systems to improve water quality and address specific contaminants
These investments are critical to maintaining system reliability and water quality for generations to come.
Contaminants of Concern
PFAS (Per- and Polyfluoroalkyl Substances)
Source: Industrial processes, firefighting foam (particularly from Truax Air Field), food packaging, and consumer products; detected at low levels in approximately half of Madison’s wells
Health Effects: Potential impacts on the immune system, hormone levels, cholesterol levels, liver function, and certain cancers with long-term exposure
Current Status: All active wells meet Wisconsin and federal standards; Well 15 remains offline while a treatment system is constructed to remove PFAS to non-detectable levels
Iron and Manganese
Source: Naturally occurring minerals in the sandstone aquifer, as well as potential contributions from landfill leachates; concentrations may increase with well pumping
Health Effects: Not considered health concerns; regulated as secondary contaminants for aesthetic reasons (taste, odor, and appearance)
Current Status: Several wells have iron and manganese levels approaching 80% of EPA secondary standards; filtration systems being added at key wells to improve water quality
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