What was found in Merced'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 |
|---|---|---|---|
| Nitrate-Nitrite | 4910 µg/L 49% of the EPA limit 10000 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2019
Highest in the city: 549147 µg/L — JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2018 | 4/4 | SYR4 |
| Nitrate | 14656.1 µg/L 147% of the EPA limit, at the 95th percentile of samples — 10000 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2019 | 4/4 | SYR4 |
| Barium | 480 µg/L 24% of the EPA limit 2000 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2019 | 4/4 | SYR4 |
| Fluoride | 256 µg/L 6.4% of the EPA limit 4000 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2019
Highest in the city: 280 µg/L — CASTLE AIRPORT · 1,650 people · 2019 | 4/4 | SYR4 |
| Copper | 181 µg/L 14% of the EPA limit 1300 µg/L Highest in the city: CASTLE AIRPORT · 1,650 people · 2019 | 2/4 | SYR4 |
| Arsenic | 8.2 µg/L 82% of the EPA limit 10 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2019
Highest in the city: 68.5 µg/L — JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2019 | 4/4 | SYR4 |
| TTHM | 9.28 µg/L 12% of the EPA limit 80 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2019
Highest in the city: 19 µg/L — JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2019 | 3/4 | SYR4 |
| Total Haloacetic Acids (HAA5) | 14 µg/L 23% of the EPA limit 60 µg/L Highest in the city: JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2019 | 1/4 | SYR4 |
| Combined Uranium | 12.4415 µg/L 41% of the EPA limit 30 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2017
Highest in the city: 13.2461 µg/L — BLACK RASCAL WATER COMPANY · 367 people · 2018 | 3/4 | SYR4 |
| Gross Beta Particle Activity | 10.23 pCi/L No EPA limit set Main supplier: CITY OF MERCED · 93,692 people · 2017 | 1/4 | SYR4 |
| Chloroform | 10.12 µg/L No EPA limit set Main supplier: CITY OF MERCED · 93,692 people · 2019 | 2/4 | SYR4 |
| Dichloroacetic Acid | 8.6 µg/L No EPA limit set Highest in the city: JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2019 | 1/4 | SYR4 |
| Chromium | 8.3 µg/L 8.3% of the EPA limit 100 µg/L Highest in the city: JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2017 | 1/4 | SYR4 |
| Dibromochloromethane | 3 µg/L No EPA limit set Main supplier: CITY OF MERCED · 93,692 people · 2019
Highest in the city: 6.1 µg/L — JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2019 | 3/4 | SYR4 |
| Dichloromethane | 4.42 µg/L 88% of the EPA limit 5 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2019 | 1/4 | SYR4 |
| Bromodichloromethane | 2.6 µg/L No EPA limit set Main supplier: CITY OF MERCED · 93,692 people · 2019
Highest in the city: 3.7 µg/L — JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2019 | 2/4 | SYR4 |
| Bromoform | 1.6 µg/L No EPA limit set Main supplier: CITY OF MERCED · 93,692 people · 2019
Highest in the city: 3 µg/L — JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2019 | 2/4 | SYR4 |
| Dibromoacetic Acid | 3 µg/L No EPA limit set Highest in the city: JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2019 | 1/4 | SYR4 |
| Trichloroacetic Acid | 2.9 µg/L No EPA limit set Highest in the city: JOHN LATORACCA CORRECTIONAL FACILITY · 800 people · 2019 | 1/4 | SYR4 |
| Tetrachloroethylene | 2.53 µg/L 51% of the EPA limit 5 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2019 | 1/4 | SYR4 |
| Trichloroethylene | 0.9930 µg/L 20% of the EPA limit 5 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2019
Highest in the city: 1.056 µg/L — CASTLE AIRPORT · 1,650 people · 2019 | 2/4 | SYR4 |
| PFHXS | 0.0150 µg/L No EPA limit set Main supplier: CITY OF MERCED · 93,692 people · 2024 | 1/4 | UCMR-5 |
| 1,2-DIBROMO-3-CHLOROPROPANE | 0.0140 µg/L 7% of the EPA limit 0.2000 µg/L Main supplier: CITY OF MERCED · 93,692 people · 2019 | 1/4 | SYR4 |
| PFOS | 0.0089 µg/L No EPA limit set Main supplier: CITY OF MERCED · 93,692 people · 2024 | 1/4 | UCMR-5 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: CITY OF MERCED · 93,692 people · 2024
Highest in the city: 0.0069 mg/L — CASTLE AIRPORT · 1,650 people · 2023 | 4/4 | LCR |
| PFOA | 0.0061 µg/L No EPA limit set Main supplier: CITY OF MERCED · 93,692 people · 2024 | 1/4 | UCMR-5 |
| Pfhxa | 0.0048 µg/L No EPA limit set Main supplier: CITY OF MERCED · 93,692 people · 2024 | 1/4 | UCMR-5 |
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 Merced
| Supplier | Population served |
|---|---|
| CITY OF MERCED | 93,692 |
| CASTLE AIRPORT | 1,650 |
| JOHN LATORACCA CORRECTIONAL FACILITY | 800 |
| BLACK RASCAL WATER COMPANY | 367 |
Frequently asked questions about Merced tap water
Is Merced tap water safe to drink?
EPA testing detected 27 contaminants in the water serving Merced. 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 Merced?
4 public water suppliers report drinking-water monitoring for Merced, California to the EPA. Each is listed above with its population served.
What contaminants are in Merced's water?
The contaminants EPA monitoring detected in Merced include Nitrate-Nitrite, Nitrate, Barium, Fluoride, Copper. 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.