What was found in Patterson's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Copper | 2839.999999999995 µg/L 218% of the EPA limit, at the 95th percentile of samples — 1300 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 2/2 | SYR4 |
| Nitrate-Nitrite | 1000 µg/L 10% of the EPA limit 10000 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Fluoride | 160 µg/L 4% of the EPA limit 4000 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Barium | 78.39999999999999 µg/L 3.9% of the EPA limit 2000 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| TTHM | 72.7 µg/L 91% of the EPA limit 80 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 2/2 | SYR4 |
| Chloroform | 53.254999999999995 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 2/2 | SYR4 |
| Total Haloacetic Acids (HAA5) | 44.305 µg/L 74% of the EPA limit 60 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 2/2 | SYR4 |
| Dalapon | 38.0848 µg/L 19% of the EPA limit 200 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Dichloroacetic Acid | 23.33 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 2/2 | SYR4 |
| Trichloroacetic Acid | 20 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 2/2 | SYR4 |
| Bromodichloromethane | 18 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 2/2 | SYR4 |
| Lead | 13.7 µg/L 91% of the EPA limit 15 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 2/2 | SYR4 |
| Dibromochloromethane | 5.394999999999996 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 2/2 | SYR4 |
| Monobromoacetic Acid | 1.3599999999999999 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019
Highest in the city: 5.1 µg/L — ST MARY PARISH W&S #2 BAYOU VISTA · 5,379 people · 2019 | 2/2 | SYR4 |
| Gross Beta Particle Activity | 4.205 pCi/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Monochloroacetic Acid | 2.795 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 2/2 | SYR4 |
| Dibromoacetic Acid | 1.8400000000000005 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019
Highest in the city: 2.235 µg/L — ST MARY PARISH W&S #2 BAYOU VISTA · 5,379 people · 2019 | 2/2 | SYR4 |
| Arsenic | 1.3599999999999999 µg/L 14% of the EPA limit 10 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Combined Uranium | 1.262 µg/L 4.2% of the EPA limit 30 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Di(2-ethylhexyl) Phthalate | 1.1389999999999998 µg/L 19% of the EPA limit 6 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Carbon Tetrachloride | 0.8100 µg/L 16% of the EPA limit 5 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Xylenes, Total | 0.6600 µg/L 0% of the EPA limit 10000 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Bromoform | 0.5800 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Combined Radium (-226 And -228) | 0.5235 pCi/L 10% of the EPA limit 5 pCi/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Selenium | 0.5100 µg/L 1% of the EPA limit 50 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Atrazine | 0.5025 µg/L 17% of the EPA limit 3 µg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2019 | 1/2 | SYR4 |
| Pfba | 0.0061 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2024
Highest in the city: 0.0069 µg/L — ST MARY PARISH W&S #2 BAYOU VISTA · 5,379 people · 2025 | 2/2 | UCMR-5 |
| Pfpea | 0.0032 µg/L No EPA limit set Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2024 | 2/2 | UCMR-5 |
| Pfhxa | 0.0030 µg/L No EPA limit set Highest in the city: ST MARY PARISH W&S #2 BAYOU VISTA · 5,379 people · 2025 | 1/2 | UCMR-5 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: CITY OF PATTERSON WATER SYSTEM · 8,456 people · 2023
Highest in the city: 0.00030 mg/L — ST MARY PARISH W&S #2 BAYOU VISTA · 5,379 people · 2025 | 2/2 | LCR |
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of the
system's samples — over 100% is worth reading, but is not by itself a
violation.
Formal violations are listed separately.
These are the utilities' own EPA-reported results, not a city-wide
average. A detection means the lab measured the
substance — it isn't the same as exceeding a legal limit. Hover a source
tag to see the EPA program and years behind each figure.
Water suppliers serving Patterson
| Supplier | Population served |
|---|---|
| CITY OF PATTERSON WATER SYSTEM | 8,456 |
| ST MARY PARISH W&S #2 BAYOU VISTA | 5,379 |
Frequently asked questions about Patterson tap water
Is Patterson tap water safe to drink?
EPA testing detected 30 contaminants in the water serving Patterson. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve Patterson?
2 public water suppliers report drinking-water monitoring for Patterson, Louisiana to the EPA. Each is listed above with its population served.
What contaminants are in Patterson's water?
The contaminants EPA monitoring detected in Patterson include Copper, Nitrate-Nitrite, Fluoride, Barium, TTHM. The full list, with the level at the main supplier and the data source, is in the table above.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.