What was found in Paso Robles'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 | 910000 µg/L 9100% of the EPA limit, at the 95th percentile of samples — 10000 µg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019 | 6/10 | SYR4 |
| Nitrate | 3845 µg/L 38% of the EPA limit 10000 µg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019
Highest in the city: 4543 µg/L — GREEN RIVER MUTUAL WATER CO. · 350 people · 2019 | 8/10 | SYR4 |
| Fluoride | 494 µg/L 12% of the EPA limit 4000 µg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019
Highest in the city: 3400 µg/L — MUSTANG SPRINGS MUTUAL WATER · 30 people · 2019 | 9/10 | SYR4 |
| Barium | 246 µg/L 12% of the EPA limit 2000 µg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019 | 4/10 | SYR4 |
| Selenium | 28.1 µg/L 56% of the EPA limit 50 µg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019
Highest in the city: 210 µg/L — RESTHAVEN MOBILE HOME PARK · 99 people · 2019 | 8/10 | SYR4 |
| TTHM | 60.52 µg/L 76% of the EPA limit 80 µg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019
Highest in the city: 73.3 µg/L — HERITAGE RANCH CSD · 2,956 people · 2019 | 4/10 | SYR4 |
| Total Haloacetic Acids (HAA5) | 18.85 µg/L 31% of the EPA limit 60 µg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019
Highest in the city: 72.6 µg/L — HERITAGE RANCH CSD · 2,956 people · 2019 | 4/10 | SYR4 |
| Copper | 60 µg/L 4.6% of the EPA limit 1300 µg/L Highest in the city: GREEN RIVER MUTUAL WATER CO. · 350 people · 2019 | 2/10 | SYR4 |
| Chloroform | 19.51 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019
Highest in the city: 56.9 µg/L — HERITAGE RANCH CSD · 2,956 people · 2019 | 3/10 | SYR4 |
| Lithium | 46.2 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2025 | 1/10 | UCMR-5 |
| Trichloroacetic Acid | 9.55 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019
Highest in the city: 41.4 µg/L — HERITAGE RANCH CSD · 2,956 people · 2019 | 3/10 | SYR4 |
| Dichloroacetic Acid | 8.67 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019
Highest in the city: 35 µg/L — HERITAGE RANCH CSD · 2,956 people · 2019 | 3/10 | SYR4 |
| Dibromochloromethane | 24.97 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019 | 4/10 | SYR4 |
| Bromoform | 24.44 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019 | 4/10 | SYR4 |
| Arsenic | 21 µg/L 210% of the EPA limit, at the 95th percentile of samples — 10 µg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019 | 7/10 | SYR4 |
| Combined Uranium | 8.5526 µg/L 29% of the EPA limit 30 µg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019
Highest in the city: 17.6863 µg/L — GREEN RIVER MUTUAL WATER CO. · 350 people · 2019 | 5/10 | SYR4 |
| Bromodichloromethane | 13.725 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019
Highest in the city: 14.29 µg/L — HERITAGE RANCH CSD · 2,956 people · 2019 | 3/10 | SYR4 |
| Dibromoacetic Acid | 10.72 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019 | 4/10 | SYR4 |
| Lead | 7.1 µg/L 47% of the EPA limit 15 µg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019 | 1/10 | SYR4 |
| Cadmium | 5.025 µg/L 101% of the EPA limit, at the 95th percentile of samples — 5 µg/L Highest in the city: RESTHAVEN MOBILE HOME PARK · 99 people · 2019 | 1/10 | SYR4 |
| Monochloroacetic Acid | 3.38 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019 | 2/10 | SYR4 |
| Monobromoacetic Acid | 2.05 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2019 | 2/10 | SYR4 |
| Chromium | 1 µg/L 1% of the EPA limit 100 µg/L Highest in the city: HERITAGE RANCH CSD · 2,956 people · 2019 | 1/10 | SYR4 |
| Combined Radium (-226 And -228) | 0.8773 pCi/L 18% of the EPA limit 5 pCi/L Highest in the city: RESTHAVEN MOBILE HOME PARK · 99 people · 2019 | 1/10 | SYR4 |
| Thallium, Total | 0.2000 µg/L 10% of the EPA limit 2 µg/L Highest in the city: HERITAGE RANCH CSD · 2,956 people · 2019 | 1/10 | SYR4 |
| Pfpea | 0.0220 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2025 | 1/10 | UCMR-5 |
| Pfhxa | 0.0200 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2025 | 1/10 | UCMR-5 |
| PFBS | 0.0081 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2025 | 1/10 | UCMR-5 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2025
Highest in the city: 0.0066 mg/L — RANCHO SALINAS MBWC · 50 people · 2024 | 10/10 | LCR |
| Pfhpa | 0.0063 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2025 | 1/10 | UCMR-5 |
| PFOA | 0.0063 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2025 | 1/10 | UCMR-5 |
| Pfba | 0.0061 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2025 | 1/10 | UCMR-5 |
| PFHXS | 0.0052 µg/L No EPA limit set Main supplier: CITY OF PASO ROBLES WATER DIVISION · 31,176 people · 2025 | 1/10 | 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 Paso Robles
| Supplier | Population served |
|---|---|
| CITY OF PASO ROBLES WATER DIVISION | 31,176 |
| HERITAGE RANCH CSD | 2,956 |
| WALNUT HILLS MUTUAL WATER CO | 486 |
| LOS ROBLES MOBILE HOME ESTATES | 420 |
| GREEN RIVER MUTUAL WATER CO. | 350 |
| RESTHAVEN MOBILE HOME PARK | 99 |
| RANCHO SALINAS MBWC | 50 |
| ALMIRA WATER ASSOCIATION | 40 |
| MUSTANG SPRINGS MUTUAL WATER | 30 |
| ADA'S LODGES | 25 |
Frequently asked questions about Paso Robles tap water
Is Paso Robles tap water safe to drink?
EPA testing detected 33 contaminants in the water serving Paso Robles. 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 Paso Robles?
10 public water suppliers report drinking-water monitoring for Paso Robles, California to the EPA. Each is listed above with its population served.
What contaminants are in Paso Robles's water?
The contaminants EPA monitoring detected in Paso Robles include Nitrate-Nitrite, Nitrate, Fluoride, Barium, Selenium. 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.