Is Chicago Tap Water Safe to Drink?
Chicago's tap water passes every federal health standard it is measured against, and the water that leaves the city's two treatment plants is close to contaminant-free. The lead that Chicago residents find at the tap is picked up on the way there — in the service line running from the street into the building, and in household plumbing. In 2025, five sampling sites exceeded the federal lead action level even though the citywide 90th percentile did not.
That distinction is the whole story of Chicago's water, and it is why the city's own water quality report opens with two full pages about lead service lines before it reaches a single test result.
Key figures — 2025 monitoring year
- Lead, 90th percentile
- 8.2 – 9.4 ppb (limit: 15 ppb action level)
- Sites above the lead action level
- 5
- Contaminants tested
- 18 — none above a federal maximum
- Violations recorded in 2025
- 3, all monitoring or reporting; the last was resolved 26 March 2026
Serving 2.7 million people, PWSID IL0316000.
Lead pathway
Where Chicago's lead actually comes from
Lead does not enter Chicago's water from Lake Michigan or from the treatment plants. It enters between the plant and the faucet. Chicago publishes enough data to show exactly where, because the city measures lead at nine points across the system every quarter — something almost no US utility does publicly.
| Where it is measured | Lead level |
|---|---|
| Treatment plant outlets — all four, Q1 and Q2 2026 | below 1 µg/L |
| Distribution mains, Q1 2026 | 1.40 – 1.74 µg/L |
| Distribution mains, Q2 2026 | 1.21 – 5.25 µg/L |
| At the tap, 90th percentile (2025) | 8.2 – 9.4 ppb |
| Highest individual sites (2025) | 5 sites above 15 ppb |
Source: City of Chicago Comprehensive Chemical Analysis Q1–Q2 2026 for plant and distribution values; Chicago Water Quality Report 2025 for tap values. 1 µg/L equals 1 ppb.
Water leaves both plants effectively lead-free. It gains one to five micrograms per litre crossing the distribution network. By the time it reaches the tap, the 90th percentile is roughly double that again — and individual homes reach several times higher. The jump between the main under the street and the glass in the kitchen is the service line and the plumbing inside the building.
The same pattern shows up in the metals that indicate pipe corrosion rather than source contamination. Iron measures below 1.3 µg/L at every plant outlet and reaches 97.1 µg/L in the north distribution system. Zinc goes from below 1 µg/L at the outlets to 51.6 µg/L in distribution. Copper follows the same curve. None of these come from Lake Michigan; they come from the pipes.
Why it is not worse: corrosion control
Chicago doses orthophosphate into treated water to keep lead out of it. Orthophosphate measures below 0.06 mg/L in raw lake water and between 1.87 and 2.27 mg/L everywhere downstream of treatment. It builds a protective mineral coating on the inside of pipes, which limits how much lead dissolves out of a lead service line.
The city needs it. The Langelier Saturation Index — a measure of whether water tends to deposit or dissolve mineral scale — runs between −0.25 and −0.62 in the distribution system. Negative values mean the water is undersaturated and would be mildly corrosive without treatment. Chicago's lead numbers are what they are because of active chemical management, not because the water is naturally benign.
North and south get different water
Chicago runs two treatment plants. The Jardine Water Purification Plant serves the northern parts of the city and suburbs; the Sawyer Water Purification Plant serves the south. The water they deliver is measurably different.
| North | South | |
|---|---|---|
| Lead | 5.25 µg/L | 1.21 µg/L |
| Iron | 69.6 µg/L | 20.5 µg/L |
| Zinc | 51.6 µg/L | 13.0 µg/L |
A citywide average conceals this. If you are on the north side, the numbers above your neighbourhood are the ones that apply to you.
Is my service line lead?
How to find out whether your service line is lead
A service line is the pipe that carries water from the water main under the street into the home. It has a public side and a private side, divided at the shut-off valve. Chicago's own guidance is a single, checkable rule: If you live in a house or two-flat built before 1986, there is a high likelihood that your water service line is lead.
You do not have to guess. The city maintains an address-level Service Line Inventory at [SLI.ChicagoWaterQuality.org](https://SLI.ChicagoWaterQuality.org) where you can look up your own property.
Chicago also offers free water lead testing to residents. Request free water lead testing by calling 311 or visiting ChicagoWaterQuality.org. Results are published at ChicagoWaterQuality.org/home#results.
Replacement programs
Chicago runs three lead service line replacement programs. Two are free.
| Program | Cost to you | Who qualifies | How to apply |
|---|---|---|---|
| Equity Lead Service Line Replacement | Free — full lead service line replacement and a new water meter | Owner-occupants of a house or two-flat with a household income below 80% of the area median income | Submit documentation of household income and home ownership at ChicagoWaterQuality.org/LSLRequity |
| Daycare Lead Service Line Replacement | Free — full lead service line replacement and new water meters | State-licensed daycares, both centers and in-home. Property owner consent is required if the daycare rents. | Daycares are on a prioritized list and the Department of Water Management contacts them proactively. |
| Homeowner-Initiated Lead Service Line Replacement | Property owner pays for the replacement; permit fees of up to $5,000 are waived | Any property with a lead service line, including rentals, owner-occupied and commercial properties | Verify the service line material, hire a licensed plumbing contractor from LeadSafeChicago.org, and have the contractor apply for the permit at ChicagoWaterQuality.org/LSLRpermit |
The homeowner-initiated program is the only one that is not free. It waives permit fees, not the cost of the replacement itself.
Full contaminant results
Every contaminant Chicago tested in 2025
Eighteen contaminants appear in Chicago's 2025 report. Sixteen were detected. None exceeded a federal maximum contaminant level.
Inorganic contaminants and metals
| Contaminant | Your water | Limit | % of limit | Range | Sampled |
|---|---|---|---|---|---|
| Lead | 8.2 – 9.4 ppb (90th percentile) | 15 ppb (action level) | 63% | 5 sites exceeding | 2025 |
| Copper | 0.52 – 0.77 ppm (90th percentile) | 1.3 ppm (action level) | 59% | 0 sites exceeding | 2025 |
| Fluoride | 0.75 ppm | 4 ppm | 19% | 0.65 – 0.75 | 2025 |
| Arsenic | 0.54 ppb | 10 ppb | 5% | 0 – 0.054 † | 2025 |
| Nitrate (as N) | 0.36 ppm | 10 ppm | 4% | 0.32 – 0.36 | 2025 |
| Total nitrate & nitrite | 0.36 ppm | 10 ppm | 4% | 0.32 – 0.36 | 2025 |
| Barium | 0.0191 ppm | 2 ppm | 1% | 0.0182 – 0.0191 | 2025 |
† The 2025 report lists arsenic with a highest detected value of 0.54 ppb and a range of 0–0.054 ppb. Both figures are reproduced as printed; the two are inconsistent by a factor of ten and we have not resolved which is intended.
Disinfection byproducts and disinfectant (Chicago Distribution System)
| Contaminant | Your water | Limit | % of limit | Range |
|---|---|---|---|---|
| Total trihalomethanes (TTHM) | 26.4 ppb | 80 ppb | 33% | 13.4 – 34.2 |
| Chlorine | 1 ppm | 4 ppm | 25% | 0 – 1 |
| Haloacetic acids (HAA5) | 13.8 ppb | 60 ppb | 23% | 7.4 – 18.8 |
TTHM and HAA5 are reported as a locational running annual average — the average of four consecutive quarterly results at each monitoring location.
Microbial and physical
| Contaminant | Your water | Limit | Status |
|---|---|---|---|
| Total Coliform Bacteria | 0.6% positive/month | 5% | Pass |
| Fecal Coliform and E. coli | 0 | 0 | Pass |
| Turbidity, lowest monthly % ≤ 0.3 NTU | 100% | Treatment technique | Pass |
| Turbidity, highest single measurement | 0.29 NTU | Treatment technique | Pass |
| Total organic carbon | Removal requirements met every month | Treatment technique | Pass |
Radiological — data from 2020
| Contaminant | Your water | Limit | % of limit | Sampled |
|---|---|---|---|---|
| Gross alpha (excl. radon, uranium) | 3.1 pCi/L | 15 pCi/L | 21% | 4 February 2020 |
| Combined radium 226/228 | 0.95 pCi/L | 5 pCi/L | 19% | 4 February 2020 |
Radiochemical monitoring runs on a six-year cycle, so these results are the most recent available and are 6 years old. The next round is due in 2026.
Secondary (aesthetic) parameters
Sulfate 27.2 ppm and sodium 9.10 ppm. Neither has a federal maximum contaminant level. Sodium is monitored so that people on sodium-restricted diets can account for it.
PFAS
No [PFAS](/contaminants/pfoa) were detected in Chicago's drinking water. Under the EPA's fifth Unregulated Contaminant Monitoring Rule, Chicago monitored for 25 per- and polyfluoroalkyl substances, 4 perfluorinated alkyl acids and lithium across four quarters of 2024. None of the 30 monitored contaminants were detected.
Cryptosporidium and Giardia
Chicago monitors its source water for Cryptosporidium, Giardia and E. coli voluntarily, beyond what is required. No Cryptosporidium or Giardia was detected in source water samples collected in 2025. The city notes that treatment is optimised to remove both, and that maintaining low turbidity substantially reduces the chance of either organism reaching the distribution system.
Violations explained
Chicago's 2025 violations
Chicago recorded three violations during 2025. None were health-based — no contaminant exceeded a maximum contaminant level. All three were monitoring or reporting failures. The city's own report is direct about it: "Our water system recently violated a drinking water standard."
Failure to monitor individual filter turbidity — April and May 2025
Interim Enhanced Surface Water Treatment Rule · 1–30 April 2025 and 1–31 May 2025 · Resolved
During two independent incidents in April and May, the system failed to continuously monitor individual filters for turbidity. There were no issues with turbidity leaving the treatment plant. Turbidity measures cloudiness and indicates whether filtration is working; it has no direct health effect but can interfere with disinfection. In both instances the monitoring issue was identified, remedied, and self-reported to the Illinois EPA.
Failure to notify residents about lead service lines — July 2025 to March 2026
Lead and Copper Rule · 15 July 2025 – 26 March 2026 · Resolved
The system failed to deliver annual notifications to all persons served by a lead service line, a galvanized service line requiring replacement, or a service line of unknown status during 2024, and could not certify that information to the state in 2025. The deadline was July 1, 2025. All notifications for lead, galvanized requiring replacement and unknown service lines were sent during 2025, and the system was certified for 2026.
This is the violation worth understanding. It carries no direct health risk, but the reason the requirement exists is that residents cannot act on a lead service line they do not know about. It is important for consumers to know whether their water is delivered through a lead, galvanized requiring replacement, or lead status unknown service line, so they can decide whether and what actions to take to reduce lead exposure. All notifications for lead, galvanized requiring replacement and unknown service lines were sent during 2025, and the system was certified for 2026.
For questions about any of these, the city lists Patrick Schwer, (312) 744-8190, 1000 East Ohio Street, Chicago, IL 60611.
Water hardness
8.2 grains per gallon · range 136–146 mg/L (USGS scale)
How hard is Chicago's water?
Chicago's water measures about 140 mg/L as calcium carbonate — roughly [8.2 grains per gallon](/tools/hardness-calculator). On the USGS scale that is hard water, but not very hard. Readings across nine sampling points in the first two quarters of 2026 ranged from 136 to 146 mg/L.
| Classification | Range |
|---|---|
| Soft | 0 – 60 mg/L |
| Moderately hard | 61 – 120 mg/L |
| Hard — Chicago at ~140 | 121 – 180 mg/L |
| Very hard | above 180 mg/L |
Hardness is not reported in Chicago's Consumer Confidence Report. These figures come from the quarterly Comprehensive Chemical Analysis, measured as CaCO₃ at both treatment plants and at three points in the distribution system.
At this level you will see scale on fixtures and inside kettles, and soap will lather less readily than in soft water. A whole-house softener will remove it, but at 140 mg/L this is a comfort and appliance-longevity decision rather than a necessary one. If your main concern is what you drink rather than what your dishwasher does, a softener is not the relevant device — see below.
Where your water comes from
Lake Michigan to your tap
Chicago draws all of its drinking water from Lake Michigan. Intake structures called water cribs, sitting roughly 2.5 miles offshore, pull deep lake water toward the city. It arrives at one of two purification plants — Jardine in the north or Sawyer in the south — and is then pushed out through the distribution network by pumping stations that maintain pressure across the city.
Lake Michigan is the only Great Lake contained entirely within the United States. It borders Illinois, Indiana, Michigan and Wisconsin, and is the second largest Great Lake by volume at 1,180 cubic miles.
Source water assessment
The Illinois EPA has completed a Source Water Assessment for Chicago's supply, and it is candid about the vulnerabilities of any surface water source. Surface water lets contaminants migrate into an intake with no protection except dilution, which is why treatment is mandatory for every surface water supply in Illinois.
For Chicago specifically, the assessment notes:
- The offshore intakes are far enough out that shoreline impacts are not usually a factor in water quality.
- Wet-weather flows and river reversals create contamination potential at certain times of year.
- The crib structures attract waterfowl, gulls and terns, which concentrates fecal deposits near the intake.
- Shore intakes, by contrast, are highly susceptible to stormwater runoff, marinas and shoreline point sources.
The full Source Water Assessment Report is available from the Department of Water Management at 312-744-6635.
Cross-connection control
The Illinois EPA requires Chicago to survey water services for cross-connections — improper or unprotected connections that could let contamination flow back into the public supply. Residents can complete the survey at chicagoccr.org/survey.
What you can do
Should you filter Chicago tap water?
If your building was built before 1986 and you have not confirmed your service line material, filtering for lead is worth doing. That is the one contaminant in Chicago with results that vary meaningfully from address to address, and the one where a citywide average tells you little about your own kitchen.
What matters, in order:
- Look up your address in the Service Line Inventory at SLI.ChicagoWaterQuality.org. This costs nothing and it is the only step that tells you about your own property rather than the city's average.
- Request the free city lead test by calling 311. Chicago provides this at no cost, which makes buying a lead test kit unnecessary unless you want faster turnaround.
- If lead is present, use a filter certified to NSF/ANSI 53 for lead reduction. Certification for taste and odour (NSF/ANSI 42) does not remove lead. Chicago's report is explicit that a filter must be certified by an ANSI-accredited certifier to be relied on for lead.
- Flush before drinking if water has been sitting in the pipes — run the tap, take a shower or run a load of laundry first. Use cold water for drinking and cooking, since hot water dissolves more lead.
- Check whether you qualify for free replacement. Removing the line is better than filtering it. Two of Chicago's three programs cost nothing.
What you probably do not need: a water softener is a hard-water appliance, not a health device, and Chicago's hardness is moderate. Reverse osmosis will remove lead, but so will a much cheaper certified carbon block, and Chicago has no contaminant profile that specifically calls for RO — no detected PFAS, no nitrate problem, no arsenic issue.
What this data does not tell you
Every number on this page describes water in the source, at the plant, in the mains, or as a citywide sampling statistic. None of it was measured in your building. Lead in particular is a property-level problem: five Chicago sites exceeded the action level in 2025 while the citywide 90th percentile stayed well under it. If you want to know about your water rather than Chicago's, the address lookup and the free test are the only two things on this page that will tell you.
Your pipes tell a different story
The data above shows what leaves the treatment plant—not what comes out of your faucet. Old pipes, lead solder, and building plumbing can add contaminants the city never tests for. Know exactly what's in your Chicago tap water.
Home test kits detect lead, bacteria, pesticides, and 100+ other contaminants. Results in 5-10 business days from certified labs.
If testing does point at a specific contaminant, our filter guides cover certifications and what to verify before buying.
Frequently asked questions
Sources and methodology
Primary sources
- *Chicago Water Quality Report 2025* (Consumer Confidence Report), City of Chicago Department of Water Management, PWSID IL0316000 — contaminant results, violations, lead and copper monitoring, source water assessment, lead service line programs, UCMR 5 results
- *Comprehensive Chemical Analysis, Q1 2026*, report dated 16 March 2026, Water Quality Division–Water Purification Laboratories, lab accreditation 100228 — multi-point sampling, hardness, corrosion indicators
- *Comprehensive Chemical Analysis, Q2 2026*, same source
- EPA Enforcement and Compliance History Online (ECHO), facility IL0316000
- Illinois EPA Drinking Water Watch
How we compiled this
We do not test water. Every figure on this page is transcribed from documents published by the City of Chicago or the EPA, and each is attributed to the document it came from. Where two published figures disagree, we show both and say so rather than choosing one — see the arsenic footnote.
Values from the Comprehensive Chemical Analysis are quarterly measurements at named sampling points. Values from the Consumer Confidence Report are annual summaries and, for lead and copper, 90th-percentile statistics across a sampling pool. These are different kinds of number and we have not averaged them together.
Radiological results are six years old because the monitoring cycle is six years. We show the sample date rather than presenting them as current.
Author: TapWater.org Editorial Team — https://www.tapwater.org/about
Data current as of: 2025 Consumer Confidence Report; supplementary data through Q2 2026
This page presents publicly available regulatory data. It is not medical advice. Water quality varies by building and over time. For official information, contact the Chicago Department of Water Management at (312) 744-8190.
Last updated: 2026-09-11