Is Thayer, IL Tap Water Safe to Drink?
Graded A-, with 8 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
85.9/100
waterverge.com Thayer, IL — Water Quality Report
Thayer's drinking water received a grade of A- (85.9 out of 100), indicating good water quality. The city's 1 water system serves approximately 721 residents using purchased surface water.
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 24 violations on record, including 4 health-based violations. 8 remain unresolved.
What to know about Thayer's water
Thayer ranks #347 out of 891 cities in Illinois for water quality, placing it mid-range 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.
As a small community water system, Thayer may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Thayer, IL water safe to drink?
Thayer's drinking water has significant quality concerns based on EPA testing data. With a grade of A- (85.9/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 721 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Thayer
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Thayer's water quality assessment. Grade: A- (85.9/100).
Contaminants: Lead and Copper Rule.
Contaminants: Lead and Copper Rule.
Contaminants: Lead and Copper Rule.
Federal disaster declaration (FEMA DR-3230). Hurricane event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-438). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Thayer's water supply.
Well within EPA limits.
Violation history
Thayer's water system has 24 total violations on record, including 4 health-based violations. 8 remain unresolved. 1 violation was issued in the last 5 years.
Flood & environmental risk
Sangamon County has experienced 2 federally declared disasters since 1974. 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 Sugar Creek.
Where does Thayer's water come from?
Thayer's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 1 water system serving approximately 721 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Sugar Creek (river).
What Thayer residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Thayer'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.
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
Sangamon County has experienced 2 federally declared disasters since 1974. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
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 |
Lead level trend (90th percentile)
See how Thayer compares by contaminant
Explore where Thayer ranks among all Illinois cities for specific contaminants.
Water source & infrastructure
Where Thayer's water comes from
Thayer'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 721 people through 1 water system.
Water bodies near Thayer
Thayer is located near 1 notable water body. As a surface water system, these water bodies may directly influence the city's drinking water supply.
Water systems serving Thayer
| System Name | PWSID | Population | Source |
|---|---|---|---|
| THAYER | IL1671250 | 721 | SWP |
How Thayer compares
Full Illinois rankings →Thayer's score of 85.9/100 is above the average of 56/100 among major Illinois cities. It outscores 9 of 10 nearby cities.
Nearby cities
View Illinois rankings →About Thayer, IL
Wikipedia →Thayer is a village in Sangamon County, Illinois, United States. As of the 2020 census, Thayer had a population of 632. It is part of the Springfield, Illinois Metropolitan Statistical Area.
Learn more about your water
Guides and resources related to Thayer's water quality findings.
Explore water quality across Sangamon
Frequently asked questions
Is Thayer, IL tap water safe to drink?
Thayer's water quality earned a grade of A- (85.9/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #347 out of 891 cities tested in Illinois.
What contaminants are in Thayer's water?
Lead was measured at 0.0 ppb (90th percentile). 24 violations are on record.
How is Thayer'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 Thayer?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Thayer's water come from?
Thayer's water is sourced from Purchased surface water. The city has 1 water system serving approximately 721 residents.
What health violations has Thayer's water system had?
Thayer has 4 health-based violations on record. The most recent violation was recorded in October 2023. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 8 violations remain unresolved.
How does Thayer's water compare to other cities?
Thayer ranks #347 out of 891 cities in Illinois (better than 61% of state cities) and #5048 out of 15744 cities nationally (68th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Thayer's small water system affect quality?
Thayer's system serves approximately 721 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 24 violations on record.