What was found in Santa Rosa'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 | 7170 µg/L 72% of the EPA limit 10000 µg/L Highest in the city: NORTH STAR MOBILE HOME PARK · 221 people · 2019 | 22/37 | SYR4 |
| Barium | 62.34 µg/L 3.1% of the EPA limit 2000 µg/L Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2015
Highest in the city: 430 µg/L — SONOMA MOUNTAIN COUNTY WATER DISTRICT · 181 people · 2019 | 18/37 | SYR4 |
| Fluoride | 244 µg/L 6.1% of the EPA limit 4000 µg/L Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2015
Highest in the city: 379.5 µg/L — ATHENA TERRACE MUTUAL WATER COMPANY · 50 people · 2013 | 27/37 | SYR4 |
| Copper | 1.98 µg/L 0.2% of the EPA limit 1300 µg/L Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2018
Highest in the city: 180 µg/L — SONOMA COUNTY CSA 41-SALMON CREEK · 427 people · 2019 | 7/37 | SYR4 |
| Total Haloacetic Acids (HAA5) | 11 µg/L 18% of the EPA limit 60 µg/L Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2019
Highest in the city: 137.62 µg/L — SONOMA COUNTY CSA 41-FREESTONE · 290 people · 2019 | 27/37 | SYR4 |
| TTHM | 36.54 µg/L 46% of the EPA limit 80 µg/L Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2019
Highest in the city: 129 µg/L — SONOMA COUNTY CSA 41-JENNER · 406 people · 2019 | 23/37 | SYR4 |
| Lithium | 96 µg/L No EPA limit set Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2024 | 1/37 | UCMR-5 |
| Chloroform | 20.415 µg/L No EPA limit set Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2019
Highest in the city: 95.75 µg/L — SONOMA COUNTY CSA 41-JENNER · 406 people · 2019 | 15/37 | SYR4 |
| Trichloroacetic Acid | 5.81 µg/L No EPA limit set Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2019
Highest in the city: 79.34 µg/L — SONOMA COUNTY CSA 41-FREESTONE · 290 people · 2019 | 12/37 | SYR4 |
| Dichloroacetic Acid | 5.4 µg/L No EPA limit set Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2019
Highest in the city: 44.83 µg/L — SONOMA COUNTY CSA 41-FREESTONE · 290 people · 2019 | 16/37 | SYR4 |
| Bromodichloromethane | 10.73 µg/L No EPA limit set Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2019
Highest in the city: 30 µg/L — SONOMA COUNTY CSA 41-JENNER · 406 people · 2019 | 17/37 | SYR4 |
| Arsenic | 3.68 µg/L 37% of the EPA limit 10 µg/L Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2018
Highest in the city: 26 µg/L — DELORES LANE WATER SYSTEM · 59 people · 2018 | 18/37 | SYR4 |
| Dibromochloromethane | 8.625 µg/L No EPA limit set Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2019
Highest in the city: 16.45 µg/L — SONOMA COUNTY CSA 41-JENNER · 406 people · 2019 | 22/37 | SYR4 |
| Trichloroethylene | 16 µg/L 320% of the EPA limit, at the 95th percentile of samples — 5 µg/L Highest in the city: EL PORTAL MOBILE ESTATES · 200 people · 2019 | 2/37 | SYR4 |
| Toluene | 12.24 µg/L 1.2% of the EPA limit 1000 µg/L Highest in the city: SONOMA COUNTY WATER AGENCY · 0 people · 2019 | 4/37 | SYR4 |
| Monobromoacetic Acid | 12 µg/L No EPA limit set Highest in the city: WILSHIRE HEIGHTS MUTUAL WATER COMPANY · 70 people · 2018 | 3/37 | SYR4 |
| Chromium | 0.6200 µg/L 0.6% of the EPA limit 100 µg/L Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2015
Highest in the city: 10.86 µg/L — KENWOOD VILLAGE WATER COMPANY (PUC) · 1,029 people · 2018 | 10/37 | SYR4 |
| Bromoform | 2.35 µg/L No EPA limit set Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2019
Highest in the city: 9.92 µg/L — SONOMA COUNTY CSA 41-SALMON CREEK · 427 people · 2019 | 17/37 | SYR4 |
| Monochloroacetic Acid | 9.69 µg/L No EPA limit set Highest in the city: SONOMA COUNTY CSA 41-FREESTONE · 290 people · 2019 | 12/37 | SYR4 |
| Gross Beta Particle Activity | 7.189 pCi/L No EPA limit set Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2015 | 1/37 | SYR4 |
| Dibromoacetic Acid | 3.12 µg/L No EPA limit set Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2019
Highest in the city: 6.64 µg/L — LEISURE MOBILE HOME PARK · 410 people · 2019 | 22/37 | SYR4 |
| 1,1-Dichloroethylene | 4.8 µg/L 69% of the EPA limit 7 µg/L Highest in the city: EL PORTAL MOBILE ESTATES · 200 people · 2019 | 1/37 | SYR4 |
| Asbestos | 2.1 MFL 30% of the EPA limit 7 MFL Highest in the city: ATHENA TERRACE MUTUAL WATER COMPANY · 50 people · 2018 | 3/37 | SYR4 |
| Gross Alpha, Excl. Radon And U | 1.2699 pCi/L 8.5% of the EPA limit 15 pCi/L Highest in the city: Kashia · 153 people · 2015 | 1/37 | SYR4 |
| Nitrite | 0.7500 µg/L 0.1% of the EPA limit 1000 µg/L Highest in the city: LEISURE MOBILE HOME PARK · 410 people · 2019 | 1/37 | SYR4 |
| Benzo(A)Pyrene | 0.1480 µg/L 74% of the EPA limit 0.2000 µg/L Highest in the city: SONOMA COUNTY WATER AGENCY · 0 people · 2019 | 1/37 | SYR4 |
| Lead | 0.0013 mg/L 8.8% of the EPA limit 0.0150 mg/L Main supplier: SANTA ROSA, CITY OF · 175,396 people · 2025
Highest in the city: 0.0080 mg/L — SONOMA MOUNTAIN COUNTY WATER DISTRICT · 181 people · 2025 | 35/37 | 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 Santa Rosa
Frequently asked questions about Santa Rosa tap water
Is Santa Rosa tap water safe to drink?
EPA testing detected 27 contaminants in the water serving Santa Rosa. 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 Santa Rosa?
37 public water suppliers report drinking-water monitoring for Santa Rosa, California to the EPA. Each is listed above with its population served.
What contaminants are in Santa Rosa's water?
The contaminants EPA monitoring detected in Santa Rosa include Nitrate, Barium, Fluoride, Copper, Total Haloacetic Acids (HAA5). 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.