Iowa Water Report Card: Worst Water Systems
The most contaminated public water systems in Iowa, ranked by PFAS levels, lead, and EPA violations from official EPA data.
Quick Answer
Iowa-American Wtr Co-Clinton District has the highest PFAS in Iowa at 647.9 ppt (162x the EPA limit). Decorah Water Department has the highest lead at 10.1 ppb. The tables below rank the worst systems in each category so you can see how your water compares.
Highest PFAS Levels in Iowa
Public water systems in Iowa with the highest peak PFAS ("forever chemical") reading in EPA UCMR5 testing (2023-2025). The EPA enforceable limit for PFOA and PFOS is 4 ppt.
| # | Water System | Location | Peak PFAS (ppt) | Compounds | vs 4 ppt limit |
|---|---|---|---|---|---|
| 1 | Iowa-American Wtr Co-Clinton District | – | 647.9 | 4 | 162x |
| 2 | Muscatine Power & Water | – | 60 | 6 | 15x |
| 3 | Sioux City Water Supply | Sioux City · 85,791 served | 35 | 9 | 9x |
| 4 | West Burlington Muni. Water Supply | – | 33 | 3 | 8x |
| 5 | Rathbun Reg Wtr Assn (Burlington) | – | 27 | 2 | 7x |
| 6 | Burlington Municipal Waterworks | – | 18 | 3 | 5x |
| 7 | Waverly Water Department | – | 15 | 5 | 4x |
| 8 | Iowa-American Wtr Co-Davenport | – | 14.8 | 2 | 4x |
| 9 | Dubuque Water Works | – | 13 | 2 | 3x |
| 10 | Waterloo Water Works | – | 13 | 2 | 3x |
| 11 | Chariton Municipal Water Works | – | 13 | 1 | 3x |
| 12 | Rathbun Reg Water Assn (Ft Madison) | – | 12 | 1 | 3x |
Highest Lead Levels in Iowa
Community water systems in Iowa with the highest 90th-percentile lead result under the EPA Lead and Copper Rule. The EPA action level is 15 ppb; there is no safe level of lead for children.
| # | Water System | Location | Lead 90th-pctile (ppb) | vs 15 ppb |
|---|---|---|---|---|
| 1 | Decorah Water Department | Decorah · 7,615 served | 10.1 | within |
| 2 | Calmar Water Supply | Calmar · 1,125 served | 9.8 | within |
| 3 | Forest City Water Supply | Forest City · 4,285 served | 8 | within |
| 4 | Clarion Water Supply | Clarion · 2,810 served | 7 | within |
| 5 | Lake Mills Municipal Water Dept-South | Lake Mills · 2,158 served | 7 | within |
| 6 | Sloan Water Supply | Sloan · 1,042 served | 6.6 | within |
| 7 | Fort Dodge Water Supply | Fort Dodge · 25,874 served | 6 | within |
| 8 | Xenia Rwd (North) | Bouton · 6,122 served | 5.5 | within |
| 9 | Sioux City Water Supply | Sioux City · 85,791 served | 5 | within |
| 10 | Sergeant Bluff Water Supply | Sergeant Bluff · 5,015 served | 4 | within |
| 11 | Northwood Waterworks | Northwood · 2,072 served | 2.2 | within |
| 12 | Manly Water Supply | Manly · 1,266 served | 2 | within |
Most EPA Violations in Iowa
Community water systems in Iowa with the most health-based EPA Safe Drinking Water Act violations on record. A health-based violation means a contaminant exceeded its federal limit or required treatment was not applied.
| # | Water System | Location | Health-based violations |
|---|---|---|---|
| 1 | Sioux City Water Supply | Sioux City · 85,791 served | 5 |
How This Report Card Is Built
PFAS rankings use EPA UCMR5 monitoring (2023-2025), showing each system's peak detection above the 4 ppt EPA limit. Lead rankings use the EPA Lead and Copper Rule 90th-percentile tap results. Violation counts come from the EPA Safe Drinking Water Information System (SDWIS) and count health-based violations. Lead and violation lists are limited to community water systems serving 1,000 or more people. Figures are the most severe on record and do not necessarily reflect current treated water.
Frequently Asked Questions
What is the most PFAS-contaminated water system in Iowa?
In EPA UCMR5 testing (2023-2025), Iowa-American Wtr Co-Clinton District had the highest recorded PFAS level in Iowa at 647.9 ppt - about 162x the EPA's 4 ppt limit for PFOA and PFOS.
Which Iowa water system has the highest lead levels?
Decorah Water Department in Decorah had the highest 90th-percentile lead result in Iowa under the EPA Lead and Copper Rule at 10.1 ppb (within the 15 ppb action level).
Which Iowa water system has the most EPA violations?
Sioux City Water Supply in Sioux City has the most health-based EPA Safe Drinking Water Act violations on record in Iowa, with 5 violations.
Where does the Iowa water report card data come from?
PFAS figures come from EPA UCMR5 monitoring (2023-2025), lead from the EPA Lead and Copper Rule 90th-percentile tap results, and violations from EPA SDWIS health-based violation records. Figures are the most severe on record and do not necessarily reflect current treated water. Check your exact address at knowyourexposure.com.
What Iowa Residents Should Do
- Look up your exact address at knowyourexposure.com for your system's data
- See the full Iowa water quality overview
- If your system is listed, a certified filter (reverse osmosis for PFAS, NSF-53 for lead) reduces exposure at the tap. See the best water filters.