Every Mississippi public water system that reported a PFAS detection during EPA UCMR 5 monitoring, how many sit above the 2024 federal limits, and the standard Mississippi applies. Concentrations are in nanograms per litre, the same unit as parts per trillion.
This is the United States view of the North American PFAS dataset. The complete dataset, including all 3,452 US systems and 97 Canadian sites, lives on the main PFAS contamination map.
Federal EPA limit applies
MDEQ follows federal MCL.
Compound
Limit (ng/L)
Note
PFOA
4
PFOS
4
PFHxS
10
PFNA
10
HFPO-DA (GenX)
10
Mixture
Not numeric
Hazard Index ≤ 1 (PFHxS, PFNA, HFPO-DA, PFBS)
US EPA, PFAS National Primary Drinking Water Regulation (2024)
US EPA PFAS National Primary Drinking Water Regulation (2024)
Last reviewed 2026-08-13. Verify against the agency source before making a compliance or remediation decision.
Full Mississippi regulatory brief
Ranked by how far the worst single compound sits above its 2024 federal limit. Values are the maximum each system reported during its UCMR 5 monitoring period.
Water system
PWSID
Worst compound
Max ng/L
Times the limit
City Of Oxford
MS0360011
PFOS
72.2
18.1x
City Of Corinth, Ms
MS0020002
PFOS
10.6
2.6x
City Of Holly Springs
MS0470002
PFOS
9.6
2.4x
Smiths Crossing Water Assn
MS0640014
PFOS
8.6
2.1x
Keesler Air Force Base
MS0240049
PFOS
7.7
1.9x
Sunrise Utility Assn Inc
MS0180013
PFOA
5.5
1.4x
University Of Mississippi
MS0360015
PFOA
5.5
1.4x
Broadmoor Utilities, Inc
MS0010005
6:2 FTS
15.5
Below limit
City Of Brookhaven
MS0430002
PFBS
4.4
Below limit
Open the full map and filter Mississippi pins
Every count above is read straight from a published government file. Nothing is modelled, averaged, or estimated. The rules below are the exact rules used to produce the figures for Mississippi.
Who is in UCMR 5. All public water systems serving more than 3,300 people, plus a national sample of 800 smaller systems. Private wells and most small systems are not monitored, so they cannot appear here.
Which systems are listed. Only systems whose state field is MS and that reported at least one measured PFAS detection. Systems that monitored and found nothing are not shown, and their absence is not evidence of contamination. That gives 9 systems in Mississippi.
Systems that cannot be placed. 87 systems nationally reported a detection but have no serviced ZIP code published by EPA, so they carry no location and are excluded from these counts. National totals on the map page include them.
Which value is used. The highest result a system reported for each compound across its sampling events. Results flagged by EPA as non-detects are excluded, as are the lithium results carried in the same file.
The above a limit count. A system is counted when its maximum result for a compound exceeds the 2024 federal Maximum Contaminant Level: 4 ng/L for PFOA and PFOS, 10 ng/L for PFHxS, PFNA, and HFPO-DA. That is 7 systems in Mississippi.
The Hazard Index count. Calculated with EPA's own mixture method for PFHxS, PFNA, HFPO-DA, and PFBS. A system is counted when the index is above 1. That is 1 system in Mississippi.
What monitoring data is not. Exceeding a 2024 limit in this dataset is not a compliance violation. The federal limits carry a 2029 compliance date, which EPA proposed on 18 May 2026 to move to 2031 for PFOA and PFOS in a rule that is not final, and treatment may have been installed since the sample was taken.
If any figure on this page does not match its source file, tell Nelson and it will be corrected or removed.
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