What was found in Atascadero'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 | 671000 µg/L 6710% of the EPA limit, at the 95th percentile of samples — 10000 µg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019
Highest in the city: 900000 µg/L — ATASCADERO STATE HOSPITAL · 4,100 people · 2019 | 3/3 | SYR4 |
| Nitrate | 2938 µg/L 29% of the EPA limit 10000 µg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019
Highest in the city: 3000 µg/L — GARDEN FARMS C.W.D. · 440 people · 2019 | 3/3 | SYR4 |
| Fluoride | 331.5 µg/L 8.3% of the EPA limit 4000 µg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 3/3 | SYR4 |
| Barium | 130 µg/L 6.5% of the EPA limit 2000 µg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 3/3 | SYR4 |
| TTHM | 60.85 µg/L 76% of the EPA limit 80 µg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 3/3 | SYR4 |
| Lithium | 20.7 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2023 | 1/3 | UCMR-5 |
| Dibromochloromethane | 20.26 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 3/3 | SYR4 |
| Total Haloacetic Acids (HAA5) | 19.1 µg/L 32% of the EPA limit 60 µg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 3/3 | SYR4 |
| Bromodichloromethane | 18.9 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 3/3 | SYR4 |
| Combined Uranium | 16.688 µg/L 56% of the EPA limit 30 µg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 2/3 | SYR4 |
| Chloroform | 15.51 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 3/3 | SYR4 |
| Selenium | 9.48 µg/L 19% of the EPA limit 50 µg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 2/3 | SYR4 |
| Dichloroacetic Acid | 9.365 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 3/3 | SYR4 |
| Dibromoacetic Acid | 8.6 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 3/3 | SYR4 |
| Bromoform | 8.25 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019
Highest in the city: 8.3 µg/L — ATASCADERO STATE HOSPITAL · 4,100 people · 2019 | 3/3 | SYR4 |
| Trichloroacetic Acid | 3.85 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019
Highest in the city: 7.23 µg/L — ATASCADERO STATE HOSPITAL · 4,100 people · 2019 | 3/3 | SYR4 |
| Arsenic | 3.28 µg/L 33% of the EPA limit 10 µg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 3/3 | SYR4 |
| Chromium | 3 µg/L 3% of the EPA limit 100 µg/L Highest in the city: ATASCADERO STATE HOSPITAL · 4,100 people · 2019 | 1/3 | SYR4 |
| Monochloroacetic Acid | 2.68 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 1/3 | SYR4 |
| Cadmium | 2.51 µg/L 50% of the EPA limit 5 µg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 2/3 | SYR4 |
| Lead | 1.2 µg/L 8% of the EPA limit 15 µg/L Highest in the city: ATASCADERO STATE HOSPITAL · 4,100 people · 2019 | 1/3 | SYR4 |
| Monobromoacetic Acid | 1 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2019 | 2/3 | SYR4 |
| Toluene | 0.5300 µg/L 0.1% of the EPA limit 1000 µg/L Highest in the city: GARDEN FARMS C.W.D. · 440 people · 2019 | 1/3 | SYR4 |
| PFHXS | 0.0076 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2023
Highest in the city: 0.0340 µg/L — ATASCADERO STATE HOSPITAL · 4,100 people · 2023 | 2/3 | UCMR-5 |
| PFOS | 0.0223 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2023
Highest in the city: 0.0330 µg/L — ATASCADERO STATE HOSPITAL · 4,100 people · 2023 | 2/3 | UCMR-5 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2025
Highest in the city: 0.0110 mg/L — GARDEN FARMS C.W.D. · 440 people · 2024 | 3/3 | LCR |
| Pfba | 0.0100 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2023 | 1/3 | UCMR-5 |
| PFBS | 0.0094 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2023 | 2/3 | UCMR-5 |
| PFOA | 0.0084 µg/L No EPA limit set Main supplier: ATASCADERO MUTUAL WATER CO · 30,618 people · 2023 | 1/3 | UCMR-5 |
| Pfpes | 0.0061 µg/L No EPA limit set Highest in the city: ATASCADERO STATE HOSPITAL · 4,100 people · 2023 | 1/3 | UCMR-5 |
| Pfhxa | 0.0036 µg/L No EPA limit set Highest in the city: ATASCADERO STATE HOSPITAL · 4,100 people · 2023 | 1/3 | 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 Atascadero
| Supplier | Population served |
|---|---|
| ATASCADERO MUTUAL WATER CO | 30,618 |
| ATASCADERO STATE HOSPITAL | 4,100 |
| GARDEN FARMS C.W.D. | 440 |
Frequently asked questions about Atascadero tap water
Is Atascadero tap water safe to drink?
EPA testing detected 31 contaminants in the water serving Atascadero. 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 Atascadero?
3 public water suppliers report drinking-water monitoring for Atascadero, California to the EPA. Each is listed above with its population served.
What contaminants are in Atascadero's water?
The contaminants EPA monitoring detected in Atascadero include Nitrate-Nitrite, Nitrate, 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.