Is Dorchester, IL Tap Water Safe to Drink?
Graded A-, with 5 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
86.7/100
waterverge.com Dorchester, IL — Water Quality Report
Dorchester's drinking water received a grade of A- (86.7 out of 100), indicating good water quality. The city's 1 water system serves approximately 562 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 8 health-based violations. 5 remain unresolved.
What to know about Dorchester's water
Dorchester ranks #311 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, Dorchester may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Dorchester, IL water safe to drink?
Dorchester's drinking water has significant quality concerns based on EPA testing data. With a grade of A- (86.7/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 562 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Dorchester
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Dorchester's water quality assessment. Grade: A- (86.7/100).
Contaminants: TTHM, Total Haloacetic Acids (HAA5).
Contaminants: Lead and Copper Rule.
Contaminants: Consumer Confidence Rule.
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 Dorchester's water supply.
Well within EPA limits.
Violation history
Dorchester's water system has 24 total violations on record, including 8 health-based violations. 5 remain unresolved. 2 violations were issued in the last 5 years.
Flood & environmental risk
Macoupin County has experienced 1 federally declared disaster since 2005. 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 Dorchester's water come from?
Dorchester's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 1 water system serving approximately 562 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment.
What Dorchester residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Dorchester'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
Top industrial polluters within 10 miles of Dorchester
Industrial polluters nearby
Reported releases to surface water by facilities near Dorchester, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
MENNEL MILLING CO OF ILLINOIS MOUNT OLIVE, IL62069 | — | — | 8.9 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Flood & disaster history
Macoupin County has experienced 1 federally declared disaster since 2005. 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 Dorchester compares by contaminant
Explore where Dorchester ranks among all Illinois cities for specific contaminants.
Water source & infrastructure
Where Dorchester's water comes from
Dorchester'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 562 people through 1 water system.
Water systems serving Dorchester
| System Name | PWSID | Population | Source |
|---|---|---|---|
| DORCHESTER | IL1170250 | 562 | SWP |
How Dorchester compares
Full Illinois rankings →Dorchester's score of 86.7/100 is above the average of 56/100 among major Illinois cities. It outscores 9 of 10 nearby cities.
Nearby cities
View Illinois rankings →About Dorchester, IL
Learn more about your water
Guides and resources related to Dorchester's water quality findings.
Explore water quality across Macoupin
Frequently asked questions
Is Dorchester, IL tap water safe to drink?
Dorchester's water quality earned a grade of A- (86.7/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #311 out of 891 cities tested in Illinois.
What contaminants are in Dorchester's water?
Lead was measured at 0.0 ppb (90th percentile). 24 violations are on record.
How is Dorchester'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 Dorchester?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Dorchester's water come from?
Dorchester's water is sourced from Purchased surface water. The city has 1 water system serving approximately 562 residents.
What health violations has Dorchester's water system had?
Dorchester has 8 health-based violations on record. The most recent violation was recorded in April 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 5 violations remain unresolved.
How does Dorchester's water compare to other cities?
Dorchester ranks #311 out of 891 cities in Illinois (better than 65% of state cities) and #4569 out of 15744 cities nationally (71th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Dorchester's small water system affect quality?
Dorchester's system serves approximately 562 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.