St. Tammany Parish Water Quality: 3 Cities Ranked by the Records
St. Tammany Parish, Louisiana: 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 EPAHighest17.3 µg/L
- CITY OF SLIDELL WATER SUPPLY17.3 µg/LSample date: 2024-10-16 to 2025-04-21
- CITY OF MANDEVILLE WATER SUPPLY14.6 µg/LSample date: 2023-11-01 to 2024-04-02
- CITY OF COVINGTON WATER SUPPLY10.5 µg/LSample date: 2025-02-25 to 2025-08-20
Lead (90th percentile)Detected in 1 system of 3 tested15 µg/L federal action level · US EPAHighest1 µg/L
- CITY OF MANDEVILLE WATER SUPPLY1 µg/LMonitoring period: 2024–2026 (still open)
- CITY OF COVINGTON WATER SUPPLYNot detectedMonitoring period: 2024–2026 (still open)
- CITY OF SLIDELL WATER SUPPLYNot detectedMonitoring period: 2022–2024
29 PFAS tested, none detected in any systemShow
Tested in these 3 systems: CITY OF COVINGTON WATER SUPPLY, CITY OF MANDEVILLE WATER SUPPLY, CITY OF SLIDELL 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 LouisianaLargest water systems
- SlidellCITY OF SLIDELL WATER SUPPLY · LA110304135,547 served
- CovingtonCITY OF COVINGTON WATER SUPPLY · LA110301116,185 served
- MandevilleCITY OF MANDEVILLE WATER SUPPLY · LA110302313,000 served
Frequently asked
How does St. Tammany Parish tap water compare across cities?
PurityMap ranks 3 cities in St. Tammany Parish 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 Slidell's main water system: CITY OF SLIDELL WATER SUPPLY · PWSID LA1103041 · Purity Score 99 (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 St. Tammany Parish cities had a PFAS sample above a 2024 EPA limit?
None of the 3 St. Tammany Parish 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 St. Tammany Parish tap water?
Utilities report lead as a 90th-percentile result from home taps. 1 of 3 St. Tammany Parish 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.
Have St. Tammany Parish water systems had drinking-water violations?
1 city in St. Tammany Parish has a health-based violation in the federal SDWIS record within about the last ten years. Each city report lists the contaminant, year and whether it was resolved.
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