Missouri Water Report Card: Worst Water Systems
The most contaminated public water systems in Missouri, ranked by PFAS levels, lead, and EPA violations from official EPA data.
Quick Answer
Ralls County Pwsd 1 has the highest PFAS in Missouri at 70.1 ppt (18x the EPA limit). Saline County Pwsd 3 has the highest lead at 2,750 ppb. The tables below rank the worst systems in each category so you can see how your water compares.
Highest PFAS Levels in Missouri
Public water systems in Missouri 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 | Ralls County Pwsd 1 | Hannibal · 7,662 served | 70.1 | 3 | 18x |
| 2 | St James Pws | St James · 3,935 served | 22.5 | 7 | 6x |
| 3 | Crystal City Pws | Crystal City · 4,733 served | 22 | 1 | 6x |
| 4 | Mercer County Pwsd 1 | Mercer · 3,200 served | 13 | 1 | 3x |
| 5 | Cape Girardeau Pws | Cape Girardeau · 39,941 served | 12.6 | 1 | 3x |
| 6 | Hannibal Pws | Hannibal · 17,108 served | 12.4 | 1 | 3x |
| 7 | Schuyler County Consolidated Pwsd 1 | Queen City · 3,482 served | 12 | 1 | 3x |
| 8 | Scotland County Cons Pwsd 1 | Memphis · 3,360 served | 12 | 1 | 3x |
| 9 | St Robert Pws | St Robert · 5,192 served | 12 | 1 | 3x |
| 10 | Cannon Pwsd 1 | Perry · 6,482 served | 11.1 | 1 | 3x |
| 11 | Marion County Pwsd 1 | Philadelphia · 4,900 served | 11 | 1 | 3x |
| 12 | Pike County Pwsd 1 | Bowling Green · 7,590 served | 11 | 1 | 3x |
Highest Lead Levels in Missouri
Community water systems in Missouri 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 | Saline County Pwsd 3 | Marshall · 3,000 served | 2,750 | 183.3x over |
| 2 | Trenton Municipal Utilities Pws | Trenton · 5,600 served | 26.4 | 1.8x over |
| 3 | Paris Pws | Paris · 1,161 served | 22.7 | 1.5x over |
| 4 | Johnson County Pwsd 2 | Holden · 12,490 served | 21.8 | 1.5x over |
| 5 | Farmington Correctional Center | Farmington · 3,500 served | 16.5 | 1.1x over |
| 6 | Gallatin Pws | Gallatin · 1,821 served | 15 | within |
| 7 | Holiday Hills Resort | Aurora · 2,065 served | 15 | within |
| 8 | Monroe County Pwsd 2 | Laddonia · 6,677 served | 14.6 | within |
| 9 | Farmington Pws | Farmington · 18,217 served | 14.2 | within |
| 10 | Hallsville Pws | Hallsville · 1,732 served | 14 | within |
| 11 | Cole County Pwsd 4 | Jefferson City · 7,568 served | 13.7 | within |
| 12 | Bonne Terre Pws | Bonne Terre · 3,537 served | 12.9 | within |
Most EPA Violations in Missouri
Community water systems in Missouri 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 | Terre Du Lac | Des Peres · 3,200 served | 81 |
| 2 | Maysville Pws | Maysville · 1,096 served | 52 |
| 3 | Bonne Terre Pws | Bonne Terre · 3,537 served | 43 |
| 4 | Farmington Pws | Farmington · 18,217 served | 40 |
| 5 | Leadwood Pws | Leadwood · 1,200 served | 31 |
| 6 | Poplar Bluff Pws | Poplar Bluff · 17,043 served | 29 |
| 7 | Monroe City Pws | Monroe · 2,500 served | 26 |
| 8 | Mo American Garden City | Joplin · 1,590 served | 26 |
| 9 | Louisiana Pws | Louisiana · 3,244 served | 21 |
| 10 | Fredericktown Pws | Fredricktown · 4,429 served | 21 |
| 11 | Cooper County Consolidated Pwsd # 1 | Boonville · 2,451 served | 20 |
| 12 | Lamar Pws | Lamar · 4,500 served | 19 |
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 Missouri?
In EPA UCMR5 testing (2023-2025), Ralls County Pwsd 1 in Hannibal had the highest recorded PFAS level in Missouri at 70.1 ppt - about 18x the EPA's 4 ppt limit for PFOA and PFOS.
Which Missouri water system has the highest lead levels?
Saline County Pwsd 3 in Marshall had the highest 90th-percentile lead result in Missouri under the EPA Lead and Copper Rule at 2,750 ppb - 183.3x the 15 ppb action level.
Which Missouri water system has the most EPA violations?
Terre Du Lac in Des Peres has the most health-based EPA Safe Drinking Water Act violations on record in Missouri, with 81 violations.
Where does the Missouri 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 Missouri Residents Should Do
- Look up your exact address at knowyourexposure.com for your system's data
- See the full Missouri 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.