Johnson County Water Quality: 3 Cities Ranked by the Records
Johnson County, Iowa: 3 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.
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 3 systems10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest390 µg/L
- CORALVILLE MUNI WATER SYSTEM390 µg/LSample date: 2023-06-12 to 2023-12-11
- NORTH LIBERTY WATER SUPPLY78 µg/LSample date: 2023-05-10 to 2023-11-08
- IOWA CITY WATER DEPARTMENT47 µg/LSample date: 2023-03-09 to 2023-12-11
Total trihalomethanes (TTHM)Detected in 1 system80 ppb federal MCL · US EPAHighest47 ppb
- IOWA CITY WATER DEPARTMENT47 ppbReporting year: 2025
Lead (90th percentile)Detected in 2 systems of 3 tested15 µg/L federal action level · US EPAHighest4 µg/L
- IOWA CITY WATER DEPARTMENT4 µg/LMonitoring period: 2021–2023
- CORALVILLE MUNI WATER SYSTEM3 µg/LMonitoring period: 2022–2024
- NORTH LIBERTY WATER SUPPLYNot detectedMonitoring period: 2023–2025
Haloacetic acids (HAA5)Detected in 1 system60 ppb federal MCL · US EPAHighest10 ppb
- IOWA CITY WATER DEPARTMENT10 ppbReporting year: 2025
Water hardnessDetected in 1 systemAesthetic, no federal health limit · USGSHighest6.5 gpg
- IOWA CITY WATER DEPARTMENT6.5 gpgReporting year: 2025
29 PFAS tested, none detected in any systemShow
Tested in these 3 systems: CORALVILLE MUNI WATER SYSTEM, IOWA CITY WATER DEPARTMENT, NORTH LIBERTY WATER SUPPLY
- 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)
- Perfluorobutanesulfonic acid (PFBS)
- Perfluorobutanoic acid (PFBA)
- 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)
- Perfluoropentanoic acid (PFPeA)
- Perfluorotetradecanoic acid (PFTA)
- Perfluorotridecanoic acid (PFTrDA)
- Perfluoroundecanoic acid (PFUnA)
Cities ranked by the records
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.
0of 3 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 Iowa1city reports hardness · Iowa City, 6.5 gpg
None above 7 gpg, the USGS threshold for hard water. An aesthetic measure with no federal health limit.
Hard water explainedLargest water systems
- Iowa CityIOWA CITY WATER DEPARTMENT · IA522507968,753 served
- North LibertyNORTH LIBERTY WATER SUPPLY · IA525207223,276 served
- CoralvilleCORALVILLE MUNI WATER SYSTEM · IA520807122,318 served
Frequently asked
How does Johnson County tap water compare across cities?
PurityMap ranks 3 cities in Johnson 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 North Liberty's main water system: NORTH LIBERTY WATER SUPPLY · PWSID IA5252072 · 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 Johnson County cities had a PFAS sample above a 2024 EPA limit?
None of the 3 Johnson 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 0.
Is there lead in Johnson County tap water?
Utilities report lead as a 90th-percentile result from home taps. 2 of 3 Johnson 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.
Does Johnson County have hard water?
Hardness is published in utility water-quality reports for 1 Johnson County city on record; the hardest is Iowa City at 6.5 grains per gallon. Hardness affects scale and appliances; it is not a health finding.
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