St. Tammany Parish, LA
drinking water quality
277,615 residents · 209 public water systems · 16 ZIP codes
EPA sampled 19 of 209 public water systems here, together serving about 193,404 people. EPA detected 6:2 FTS at 8.2 ng/L. EPA has not set a drinking water limit for 6:2 FTS, so there is no figure to compare it against. Last sampled 9/9/2025.
Health-based violations
Separately from PFAS, EPA records 167 health-based violations across 63 of the parish’s water systems since 2020, the most recent in 2026. They involved contaminant 0700, lead and copper, E. coli, trihalomethanes, haloacetic acids, contaminant 0999.
What this means
PFAS are industrial chemicals that EPA describes as breaking down only very slowly in the environment. In April 2024 EPA set the first enforceable national limits: 4 ng/L for PFOA and PFOS, 10 ng/L for PFHxS, PFNA and GenX.
These figures are county-level and come from EPA’s sampling of public water systems. They describe the worst result found in the county, not what comes out of any particular tap — that depends on which system serves the address, and on the plumbing in the building. A private well is not covered by this programme at all.
ZIP codes in St. Tammany Parish
70420 · 70431 · 70433 · 70435 · 70437 · 70445 · 70447 · 70448 · 70452 · 70457 · 70458 · 70460 · 70461 · 70463 · 70464 · 70471
Readings are parish-level, so every ZIP here shares the figure above. Search your ZIP on the map to see it in context.