Is Walnut, IL Tap Water Safe to Drink?
Graded B+ — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
82.2/100
waterverge.com Walnut, IL — Water Quality Report
Walnut's drinking water received a grade of B+ (82.2 out of 100), indicating good water quality. The city's 1 water system serves approximately 1,311 residents using groundwater.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 11 violations on record, including 3 health-based violations. 4 remain unresolved.
What to know about Walnut's water
Walnut ranks #497 out of 891 cities in Illinois for water quality, placing it below average in the state.
Walnut relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
As a small community water system, Walnut may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Walnut, IL water safe to drink?
Walnut's drinking water has significant quality concerns based on EPA testing data. With a grade of B+ (82.2/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 1,311 residents using groundwater (wells).
Recent water quality updates for Walnut
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Walnut's water quality assessment. Grade: B+ (82.2/100).
Contaminants: Consumer Confidence Rule.
Contaminants: TTHM, Total Haloacetic Acids (HAA5).
Contaminants: Consumer Confidence Rule.
Federal disaster declaration (FEMA DR-4461). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-4116). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Walnut'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
Walnut's water system has 11 total violations on record, including 3 health-based violations. 4 remain unresolved. 5 violations were issued in the last 5 years.
Flood & environmental risk
Bureau County has experienced 7 federally declared disasters since 1973. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies.
Where does Walnut's water come from?
Walnut's drinking water comes from groundwater (wells), supplied by 1 water system serving approximately 1,311 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate.
What Walnut residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Walnut'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.
Walnut'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 ↓Violation summary
Violations & advisories
Flood & disaster history
Bureau County has experienced 7 federally declared disasters since 1973. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Walnut'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. | 1.46 | 1.3 | mg/L | Inorganic | Over Limit |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Walnut compares by contaminant
Explore where Walnut ranks among all Illinois cities for specific contaminants.
Water source & infrastructure
Where Walnut's water comes from
Walnut's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by local government ownership and serves approximately 1,311 people through 1 water system.
Water systems serving Walnut
| System Name | PWSID | Population | Source |
|---|---|---|---|
| WALNUT | IL0111100 | 1,311 | GW |
How Walnut compares
Full Illinois rankings →Walnut's score of 82.2/100 is above the average of 56/100 among major Illinois cities. It outscores 8 of 10 nearby cities.
Nearby cities
View Illinois rankings →About Walnut, IL
Wikipedia →Walnut is a village in Bureau County, Illinois, United States. The residents of Walnut are known as "Walnutions" a unique demonym. The population was 1,311 at the 2020 census, down from 1,416 at the 2010 census and 1,461 at the 2000 census. It is part of the Ottawa Micropolitan Statistical Area. The village was incorporated on October 26, 1876.
Learn more about your water
Guides and resources related to Walnut's water quality findings.
Explore water quality across Bureau
Frequently asked questions
Is Walnut, IL tap water safe to drink?
Walnut's water quality earned a grade of B+ (82.2/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #497 out of 891 cities tested in Illinois.
What contaminants are in Walnut's water?
Lead was measured at 0.0 ppb (90th percentile). 11 violations are on record.
How is Walnut'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 Walnut?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Walnut's water come from?
Walnut's water is sourced from Groundwater. The city has 1 water system serving approximately 1,311 residents.
What health violations has Walnut's water system had?
Walnut has 3 health-based violations on record. The most recent violation was recorded in July 2024. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 4 violations remain unresolved.
Is Walnut's groundwater at risk of contamination?
Walnut uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 11 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Walnut's water compare to other cities?
Walnut ranks #497 out of 891 cities in Illinois (better than 44% of state cities) and #7130 out of 15744 cities nationally (55th percentile). The grade of B+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Walnut's small water system affect quality?
Walnut's system serves approximately 1,311 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 11 violations on record.