Updated 2026-10-15
County water report

Monroe County Water Quality: 2 Cities Ranked by the Records

Monroe County, Illinois: 2 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.

Across the county's systems

Highest result for each contaminant

One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.

LithiumDetected in 2 systems10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest28.2 µg/L
  • COLUMBIA28.2 µg/LSample date: 2024-10-22 to 2025-06-09
  • WATERLOO19.5 µg/LSample date: 2024-04-22 to 2025-02-25
Lead (90th percentile)Detected in 1 system of 2 tested15 µg/L federal action level · US EPAHighest1.1 µg/L
  • WATERLOO1.1 µg/LMonitoring period: 2026–2028 (still open)
  • COLUMBIANot detectedMonitoring period: 2025–2025
Perfluorobutanesulfonic acid (PFBS)Detected in 1 system of 2 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest3.4 ng/L
  • COLUMBIA3.4 ng/LSample date: 2024-10-22 to 2025-06-09
  • WATERLOONot detected · below 3.0 ng/L lab reporting limitSample date: 2024-04-22 to 2025-02-25
Perfluorobutanoic acid (PFBA)Detected in 2 systemsNo federal or state limit; shown for transparencyHighest16.9 ng/L
  • WATERLOO16.9 ng/LSample date: 2024-04-22 to 2025-02-25
  • COLUMBIA11.5 ng/LSample date: 2024-10-22 to 2025-06-09
Perfluoropentanoic acid (PFPeA)Detected in 1 system of 2 testedNo federal or state limit; shown for transparencyHighest3.2 ng/L
  • WATERLOO3.2 ng/LSample date: 2024-04-22 to 2025-02-25
  • COLUMBIANot detected · below 3.0 ng/L lab reporting limitSample date: 2024-10-22 to 2025-06-09
26 PFAS tested, none detected in any systemShow

Tested in these 2 systems: COLUMBIA, WATERLOO

  • 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
  • 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
  • 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
  • 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
  • 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
  • 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
  • Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
  • N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
  • N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
  • Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
  • Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
  • Perfluoro-3-methoxypropanoic acid (PFMPA)
  • Perfluoro-4-methoxybutanoic acid (PFMBA)
  • Perfluorodecanoic acid (PFDA)
  • Perfluorododecanoic acid (PFDoA)
  • Perfluoroheptanesulfonic acid (PFHpS)
  • Perfluoroheptanoic acid (PFHpA)
  • Perfluorohexanesulfonic acid (PFHxS)
  • Perfluorohexanoic acid (PFHxA)
  • Perfluorononanoic acid (PFNA)
  • Perfluorooctanesulfonic acid (PFOS)
  • Perfluorooctanoic acid (PFOA)
  • Perfluoropentanesulfonic acid (PFPeS)
  • Perfluorotetradecanoic acid (PFTA)
  • Perfluorotridecanoic acid (PFTrDA)
  • Perfluoroundecanoic acid (PFUnA)
2 cities

Cities ranked by the records

Showing 2 of 2 cities · scores are system-level, not tap tests

Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.

PFAS in Monroe CountyPFAS detected in 2 of 2 cities; none had a sample above a 2024 EPA limit
4.0 ng/L federal MCL · PFOS, ng/LPFAS in Illinois
Lead

0of 2 cities above the 15 µg/L action level

Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.

Lead in Illinois
Who supplies the county

Largest water systems

  1. ColumbiaCOLUMBIA · IL1330050
    11,129 served
  2. WaterlooWATERLOO · IL1330300
    10,190 served
Questions

Frequently asked

How does Monroe County tap water compare across cities?

PurityMap ranks 2 cities in Monroe County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Columbia's main water system: COLUMBIA · PWSID IL1330050 · Purity Score 100 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.

How many Monroe County cities had a PFAS sample above a 2024 EPA limit?

None of the 2 Monroe County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing. PFAS were detected below the limit in 2.

Is there lead in Monroe County tap water?

Utilities report lead as a 90th-percentile result from home taps. 1 of 2 Monroe County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.

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