Is Darien, IL Tap Water Safe to Drink?
Graded C+ — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
69.2/100
waterverge.com Darien, IL — Water Quality Report
Darien's drinking water received a grade of C+ (69.2 out of 100), indicating fair water quality. The city's 6 water systems serve approximately 33,723 residents using purchased surface water.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. PFAS testing under UCMR 5 found no detectable forever chemicals.
The system has 57 violations on record, including 6 health-based violations. 12 remain unresolved.
What to know about Darien's water
Darien ranks #745 out of 891 cities in Illinois for water quality, placing it among the lowest-rated in the state.
The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection.
Hexavalent chromium (chromium-6) was detected at 0.27 µg/L in UCMR 3 testing. While below California's 10 µg/L limit and with no federal MCL set, residents sensitive to this contaminant may consider reverse osmosis filtration.
The system has seen 11 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Darien, IL water safe to drink?
Darien's drinking water has significant quality concerns based on EPA testing data. With a grade of C+ (69.2/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 6 water systems serve approximately 33,723 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Darien
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Darien's water quality assessment. Grade: C+ (69.2/100).
Contaminants: Consumer Confidence Rule.
Contaminants: Total Haloacetic Acids (HAA5).
Contaminants: Consumer Confidence Rule.
Federal disaster declaration (FEMA DR-4116). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-3230). Hurricane event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Darien's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Darien's water system has 57 total violations on record, including 6 health-based violations. 12 remain unresolved. 11 violations were issued in the last 5 years.
Flood & environmental risk
DuPage County has experienced 5 federally declared disasters since 1972. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Des Plaines River, Salt Creek, Addison Creek, Flag Creek, Sawmill Creek.
Where does Darien's water come from?
Darien's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 6 water systems serving approximately 33,723 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Des Plaines River (river), Salt Creek (river), Addison Creek (river), Flag Creek (river), Sawmill Creek (river).
What Darien residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Darien's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Darien's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Forever chemicals overview
National PFAS report →Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Darien
Industrial polluters nearby
Reported releases to surface water by facilities near Darien, ranked by pounds discharged annually.
Total reported releases to surface water: 169,755 lbs
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
CITGO PETROLEUM CORP LEMONT REFINERY LEMONT, IL60439 | Nitrate compounds (water dissociable; reportable only when in aqueous solution) | 169,739 | 8.0 mi |
K.A. STEEL CHEMICALS INC. D/B/A OLIN CHLOR ALKALI PRODUCTS & LEMONT, IL60439 | Chlorine | 8 | 4.7 mi |
SIGNODE INDUSTRIAL GROUP LLC BRIDGEVIEW, IL60455 | Lead And Lead Compounds | 7 | 8.8 mi |
ARROW GEAR DOWNERS GROVE, IL60515 | Lead | 1 | 4.4 mi |
DUBOIS CHEMICALS INC. - BEDFORD PARK IL BEDFORD PARK, IL60638 | — | — | 9.6 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Superfund sites within 10 miles of Darien
Superfund sites nearby
Federally tracked hazardous-waste sites on the EPA National Priorities List. Proximity does not necessarily indicate tap-water contamination — the connection depends on hydrology and treatment.
- LENZ OIL SERVICE INC3.4 mi
Source: EPA Superfund National Priorities List
Flood & disaster history
DuPage County has experienced 5 federally declared disasters since 1972. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Darien's water supply, we recommend the following filter types.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.0 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 1.62 | 1.3 | mg/L | Inorganic | Over Limit |
| 11Cl-PF3OUdS | ND | HI | µg/L | PFAS | Not Detected |
| 4:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 6:2 FTS 6:2 FTSPFAS A fluorotelomer sulfonate commonly found at sites contaminated with aqueous film-forming foam (AFFF) used in firefighting. Health EffectsPotential liver toxicity and endocrine disruption. Less studied but identified as a contaminant of concern. EPA LimitNo individual MCL (not yet regulated) Common SourcesFirefighting foam (AFFF), airports, military bases, and industrial facilities. | ND | HI | µg/L | PFAS | Not Detected |
| 8:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 9Cl-PF3ONS | ND | HI | µg/L | PFAS | Not Detected |
| ADONA | ND | HI | µg/L | PFAS | Not Detected |
| HFPO-DA HFPO-DA (GenX)PFAS A replacement for PFOA in manufacturing, marketed as safer but still a persistent "forever chemical." Also known as GenX. Health EffectsLiver and kidney effects, reproductive toxicity, immune system effects, and potential cancer risk. EPA Limit10 ppt MCL Common SourcesFluoropolymer manufacturing (used as PFOA replacement), industrial wastewater discharge. | ND | 0.01 | µg/L | PFAS | Not Detected |
| lithium LithiumInorganic A naturally occurring alkali metal found in groundwater. Monitored under UCMR 5 to assess occurrence in drinking water. Health EffectsKidney effects at high doses. Low-level exposure effects under study; some research suggests neurological effects. EPA LimitNo MCL (monitoring only under UCMR 5) Common SourcesNatural mineral deposits, geothermal water, and industrial discharge. | ND | HI | µg/L | PFAS | Not Detected |
| NEtFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| NFDHA | ND | HI | µg/L | PFAS | Not Detected |
| NMeFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| PFBA PFBAPFAS One of the shortest-chain PFAS compounds. Very mobile in water and difficult to remove with standard filtration. Health EffectsThyroid effects, potential developmental toxicity. Shorter half-life in body than long-chain PFAS. EPA LimitNo individual MCL (not yet regulated) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and firefighting foam. | ND | HI | µg/L | PFAS | Not Detected |
| PFBS PFBSPFAS A short-chain PFAS used as a replacement for PFOS. While it clears the body faster than long-chain PFAS, it still persists in the environment. Health EffectsThyroid effects, reproductive and developmental toxicity, kidney effects. EPA LimitPart of Hazard Index (1.0) Common SourcesIndustrial discharge, firefighting foam, and as a replacement chemical in manufacturing. | ND | HI | µg/L | PFAS | Not Detected |
| PFDA | ND | HI | µg/L | PFAS | Not Detected |
| PFDoA | ND | HI | µg/L | PFAS | Not Detected |
| PFEESA | ND | HI | µg/L | PFAS | Not Detected |
| PFHpA PFHpAPFAS A medium-chain PFAS compound found in various environmental samples. Less studied than PFOA/PFOS but still considered a contaminant of concern. Health EffectsLiver effects, potential developmental toxicity, and endocrine disruption. EPA LimitPart of Hazard Index (1.0) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFHpS | ND | HI | µg/L | PFAS | Not Detected |
| PFHxA PFHxAPFAS A short-chain PFAS replacement chemical widely used after manufacturers phased out longer-chain PFAS. Very commonly detected in water. Health EffectsLiver and kidney effects, potential thyroid disruption. Considered less toxic than long-chain PFAS but still persistent. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial processes, firefighting foam (AFFF), food packaging, and textile treatment. | ND | HI | µg/L | PFAS | Not Detected |
| PFHxS PFHxSPFAS A medium-chain PFAS found in firefighting foam and consumer products. It has a long half-life in the human body, similar to long-chain PFAS. Health EffectsImmune system effects, thyroid disruption, and potential reproductive and developmental harm. EPA LimitPart of Hazard Index (1.0) Common SourcesFirefighting foam (AFFF), waterproof textiles, food packaging, and industrial discharge. | ND | HI | µg/L | PFAS | Not Detected |
| PFMBA | ND | HI | µg/L | PFAS | Not Detected |
| PFMPA | ND | HI | µg/L | PFAS | Not Detected |
| PFNA PFNAPFAS A long-chain PFAS compound used in manufacturing fluoropolymers. It bioaccumulates in the body and is very persistent in the environment. Health EffectsDevelopmental effects, liver toxicity, immune suppression, and potential cancer risk. EPA LimitPart of Hazard Index (1.0) Common SourcesFluoropolymer manufacturing, industrial emissions, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFOA PFOAPFAS A long-chain PFAS ("forever chemical") once widely used in nonstick coatings and firefighting foam. It persists in the body and environment for years. Health EffectsLinked to kidney and testicular cancer, thyroid disease, elevated cholesterol, and reproductive issues. EPA Limit4.0 ppt MCL Common SourcesIndustrial discharge, firefighting foam (AFFF), nonstick cookware manufacturing, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFOS PFOSPFAS A long-chain PFAS compound historically used in stain-resistant coatings and firefighting foam. One of the most studied and persistent PFAS chemicals. Health EffectsLiver damage, immune system suppression, thyroid disruption, increased cholesterol, and potential cancer risk. EPA Limit4.0 ppt MCL Common SourcesFirefighting foam (AFFF), industrial sites, stain-resistant fabric treatments, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFPeA PFPeAPFAS A short-chain PFAS compound commonly detected in drinking water. One of the most frequently found PFAS in UCMR 5 monitoring. Health EffectsLess studied than PFOA/PFOS. Potential liver and thyroid effects. Research is ongoing. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial discharge, firefighting foam degradation, and consumer products. | ND | HI | µg/L | PFAS | Not Detected |
| PFPeS | ND | HI | µg/L | PFAS | Not Detected |
| PFTA | ND | HI | µg/L | PFAS | Not Detected |
| PFTrDA | ND | HI | µg/L | PFAS | Not Detected |
| PFUnA | ND | HI | µg/L | PFAS | Not Detected |
Lead level trend (90th percentile)
Copper level (90th percentile)
Latest reading: 1.620 mg/L (1994)
EPA action level: 1.3 mg/L
See how Darien compares by contaminant
Explore where Darien ranks among all Illinois cities for specific contaminants.
Water source & infrastructure
Where Darien's water comes from
Darien's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards.
These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge.
The system is operated by local government ownership and serves approximately 33,723 people through 6 water systems.
Water bodies near Darien
Darien is located near 5 notable water bodies. As a surface water system, these water bodies may directly influence the city's drinking water supply.
Water systems serving Darien
| System Name | PWSID | Population | Source |
|---|---|---|---|
| DARIEN | IL0430270 | 21,751 | SWP |
| SOUTHEAST REGIONAL WATER FACILITY | IL0430060 | 6,940 | SWP |
| GLEN ELLYN HEIGHTS SUBDIVISION | IL0435500 | 1,931 | SWP |
| STEEPLE RUN SBDV | IL0437160 | 1,931 | SWP |
| NORTH REGIONAL WATER FAC | IL0435850 | 770 | GW |
| HOBSON VALLEY WATER SYSTEM | IL0430040 | 400 | SWP |
How Darien compares
Full Illinois rankings →Darien's score of 69.2/100 is above the average of 56/100 among major Illinois cities. It outscores 7 of 10 nearby cities.
Nearby cities
View Illinois rankings →About Darien, IL
Wikipedia →Darien is a city in DuPage County, Illinois, United States. Per the 2020 census, the population was 22,011. A southwestern suburb of Chicago, Darien was named after the town of Darien, Connecticut. Darien is just north of I-55 and Historic U.S. Route 66. The entire south edge of the town borders Waterfall Glen.
Learn more about your water
Guides and resources related to Darien's water quality findings.
Explore water quality across Dupage
Frequently asked questions
Is Darien, IL tap water safe to drink?
Darien's water quality earned a grade of C+ (69.2/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #745 out of 891 cities tested in Illinois.
What contaminants are in Darien's water?
Lead was measured at 0.0 ppb (90th percentile). No PFAS compounds were detected. 57 violations are on record.
How is Darien's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Darien?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Darien's water come from?
Darien's water is sourced from Purchased surface water. The city has 6 water systems serving approximately 33,723 residents.
What health violations has Darien's water system had?
Darien has 6 health-based violations on record. The most recent violation was recorded in July 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 12 violations remain unresolved.
How does Darien's water compare to other cities?
Darien ranks #745 out of 891 cities in Illinois (better than 16% of state cities) and #10950 out of 15744 cities nationally (31th percentile). The grade of C+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.