Chicago – Illinois
Chicago manages one of America’s largest municipal water systems, serving approximately 5.3 million people across the city and 125 surrounding suburbs. The Chicago Department of Water Management (CDWM) delivers nearly one billion gallons of water daily through a vast network of purification plants, pumping stations, and more than 4,400 miles of water mains.
Drawing from Lake Michigan, a freshwater source containing roughly 1.3 quadrillion gallons of water, Chicago’s water undergoes rigorous treatment at either the Jardine Water Purification Plant (the world’s largest) or the South Water Purification Plant. The city’s water infrastructure includes a unique engineering feat – a series of tunnels and reservoirs deep below the city that help manage stormwater and prevent sewage overflows into Lake Michigan.
Chicago Water Quality: Current Status (2024-2025)
Latest Testing Results
- Lead Levels: The most recent testing period (January-December 2023) showed 90th percentile lead levels of 9.1 parts per billion (ppb), below the EPA action level of 15 ppb but higher than many other major U.S. cities.
- Testing Scope: The city conducts over 600,000 analyses per year on water samples collected throughout the distribution system, including residential tap water in homes with and without lead service lines.
- Compliance Status: Chicago’s water meets all EPA standards for regulated contaminants. The city’s extensive monitoring program tests for over 200 substances, including microbes, metals, chemicals, and radionuclides.
Lead Service Line Challenges
- Scope of the Issue: Chicago has approximately 400,000 lead service lines connecting homes to water mains – more than any other U.S. city. These lines were mandated by city plumbing code until 1986.
- Replacement Program: The city launched an accelerated Lead Service Line Replacement Program in 2021 with a target to replace all lead service lines over the next 50 years, prioritizing low-income areas and homes with elevated lead levels.
- Current Progress: As of early 2025, approximately 8,000 lead service lines have been replaced. The program’s pace has increased with additional federal infrastructure funding, with plans to replace over 30,000 lines by 2028.
Water Source and Treatment
- Lake Michigan Water Quality: Lake Michigan provides a consistently high-quality source water with low turbidity and mineral content. The Great Lakes Water Quality Agreement between the U.S. and Canada helps protect this critical resource.
- Treatment Process: Chicago’s water treatment includes coagulation, flocculation, sedimentation, filtration, and disinfection. The city has used chlorine as its primary disinfectant since 1912.
- Corrosion Control: Chicago adds orthophosphate to its water to create a protective coating inside pipes, reducing lead leaching. The dosage was optimized in 2023 based on comprehensive pipe loop studies.
Infrastructure Investments
- Water Main Replacement: Chicago is replacing approximately 30 miles of water mains annually, focusing on pipes installed before 1950 that have the highest break rates.
- Facilities Modernization: The Jardine Water Purification Plant is undergoing a $600 million modernization project to enhance treatment processes and improve energy efficiency, scheduled for completion in 2027.
- Smart Meters: The city has installed over 500,000 smart water meters to help detect leaks early and improve conservation efforts.
Emerging Contaminant Monitoring
Chicago actively monitors for emerging contaminants including microplastics, PFAS, pharmaceuticals, and personal care products at levels well below health guidelines. The city is partnering with research institutions to study treatment technologies for these compounds, keeping ahead of potential regulatory changes.
Recommendations for Chicago Residents
Use Filtered Water
If your home has lead service lines or was built before 1987, use NSF-certified filters for drinking and cooking water. Look for filters certified to remove lead (Standard 53) and ensure they’re properly maintained.
Test Your Water
Chicago residents can request free water quality testing by calling 311 or visiting www.chicago.gov/waterlead to schedule testing. Testing is particularly important for homes with children or pregnant women.
Check Your Service Line
Determine if your home has a lead service line using Chicago’s online lookup tool at www.chicago.gov/leadcheck. Eligible homeowners can apply for the city’s lead service line replacement program.
Flush Your Pipes
After water hasn’t been used for 6 hours or more, run cold water for 3-5 minutes to flush stagnant water. Always use cold water for drinking and cooking, as hot water may contain higher levels of lead.
Stay Informed
Review Chicago’s annual Consumer Confidence Report for detailed water quality information. Sign up for water quality alerts at www.chicago.gov/wateralerts to receive notifications about testing results or potential issues.
Frequently Asked Questions
How do I know if my home has a lead service line?
Chicago homes built before 1987 likely have lead service lines due to past city requirements. To check your specific home:
1. Look at the water service line entering your home (usually in the basement near the water meter). Lead pipes are dull gray, won’t attract a magnet, and scratch easily with a key, revealing a silver color.
2. Use Chicago’s online lookup tool at www.chicago.gov/leadcheck to see if your address is in the database.
3. Call 311 to request a free evaluation from the Department of Water Management.
Is Chicago’s water safe to drink despite lead service lines?
Chicago’s water meets all federal and state drinking water standards and is treated with orthophosphate to minimize lead leaching from pipes. However, homes with lead service lines may experience varying lead levels, particularly after water has been sitting in pipes for several hours.
As a precaution, especially for households with children, pregnant women, or immunocompromised individuals, the Chicago Department of Public Health recommends using NSF-certified water filters for drinking and cooking if you have lead service lines. Always run water for 3-5 minutes after long periods of non-use before collecting water for consumption.
How can I participate in Chicago’s lead service line replacement program?
Chicago offers several programs to help residents replace lead service lines:
1. Equity Lead Service Line Replacement Program: Free replacements for low-income households in prioritized areas. Eligibility is based on income (at or below 80% of area median income).
2. Homeowner-Initiated Program: The city waives up to $3,100 in permit fees and tap costs when homeowners hire a licensed plumber to replace their lead service line.
3. MeterSave Program: Free lead service line replacement when you volunteer to have a water meter installed.
Visit www.chicago.gov/leadpipes or call 311 to apply for these programs.
What types of water filters are effective for removing lead?
For lead removal, look for filters that are certified to NSF/ANSI Standard 53 for lead reduction. Effective filter types include:
1. Pitcher filters: Affordable and easy to use, but require regular filter replacement (typically every 2-3 months).
2. Faucet-mounted filters: Attach directly to your faucet and allow you to switch between filtered and unfiltered water. Filter cartridges typically last 2-3 months.
3. Under-sink filters: More expensive but longer-lasting and higher-capacity options that filter water at a single faucet.
Ensure whatever filter you choose explicitly states it removes lead and is certified to NSF/ANSI Standard 53. Always follow the manufacturer’s instructions for replacement schedules.
Contaminants of Concern
Lead
Source: Primarily from lead service lines connecting homes to water mains, also from lead solder and fixtures in older homes
Health Effects: Developmental delays in children, learning difficulties, reduced IQ, kidney damage, reproductive issues, and cardiovascular effects in adults
Current Levels: 90th percentile value of 9.1 ppb EPA Limit: Action level 15 ppb, but no level of lead is considered safe
Disinfection Byproducts
Source: Form when chlorine used for disinfection reacts with naturally occurring organic matter in water
Health Effects: Potential increased risk of bladder cancer and reproductive effects with long-term exposure to elevated levels
Current Status: Below EPA limits but present in Chicago’s water; levels vary seasonally and are higher in summer months
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