What was found in Modesto'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 | 8435 µg/L 84% of the EPA limit 10000 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2018
Highest in the city: 691410 µg/L — PARK HEIGHTS MUTUAL WATER CO · 250 people · 2019 | 13/17 | SYR4 |
| Nitrate | 8382.07 µg/L 84% of the EPA limit 10000 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 19000 µg/L — CITY OF MODESTO - GRAYSON · 914 people · 2019 | 15/17 | SYR4 |
| Barium | 240 µg/L 12% of the EPA limit 2000 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 499 µg/L — COUNTRY WESTERN MHRV · 55 people · 2017 | 9/17 | SYR4 |
| Fluoride | 175 µg/L 4.4% of the EPA limit 4000 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 345 µg/L — CITY OF WATERFORD · 8,788 people · 2018 | 10/17 | SYR4 |
| TTHM | 74.3525 µg/L 93% of the EPA limit 80 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 11/17 | SYR4 |
| Chloroform | 71.0875 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 4/17 | SYR4 |
| Total Haloacetic Acids (HAA5) | 43.325 µg/L 72% of the EPA limit 60 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 46.6 µg/L — MODESTO IRRIGATION DISTRICT · 23 people · 2019 | 6/17 | SYR4 |
| Combined Uranium | 34.27 µg/L 114% of the EPA limit, at the 95th percentile of samples — 30 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 35.76 µg/L — RIVERDALE PARK TRACT CSD · 610 people · 2019 | 12/17 | SYR4 |
| Dichloroacetic Acid | 23.86 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 24.8 µg/L — MODESTO IRRIGATION DISTRICT · 23 people · 2019 | 3/17 | SYR4 |
| Arsenic | 7.4 µg/L 74% of the EPA limit 10 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 24.6 µg/L — COUNTRY WESTERN MHRV · 55 people · 2019 | 12/17 | SYR4 |
| Trichloroethylene | 24.1 µg/L 482% of the EPA limit, at the 95th percentile of samples — 5 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 1/17 | SYR4 |
| Trichloroacetic Acid | 22.27 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 3/17 | SYR4 |
| Lithium | 21 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2024 | 2/17 | UCMR-5 |
| Chromium | 6.4 µg/L 6.4% of the EPA limit 100 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 20.85 µg/L — CITY OF MODESTO - GRAYSON · 914 people · 2017 | 5/17 | SYR4 |
| Tetrachloroethylene | 15 µg/L 300% of the EPA limit, at the 95th percentile of samples — 5 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 1/17 | SYR4 |
| Selenium | 6.12 µg/L 12% of the EPA limit 50 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 13.565 µg/L — COUNTRY WESTERN MHRV · 55 people · 2017 | 4/17 | SYR4 |
| Bromodichloromethane | 5.57 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 4/17 | SYR4 |
| Bromoform | 3.9155 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 5.01 µg/L — HILLSVIEW HOMES · 887 people · 2019 | 9/17 | SYR4 |
| Monochloroacetic Acid | 4.92 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 3/17 | SYR4 |
| Dibromochloromethane | 4.7525 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 5/17 | SYR4 |
| Dibromoacetic Acid | 2.34 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 4.6 µg/L — CITY OF MODESTO - GRAYSON · 914 people · 2019 | 6/17 | SYR4 |
| Gross Beta Particle Activity | 3.557 pCi/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2017 | 2/17 | SYR4 |
| Beryllium, Total | 2 µg/L 50% of the EPA limit 4 µg/L Highest in the city: MORNINGSIDE MOBILEHOME PARK · 67 people · 2017 | 1/17 | SYR4 |
| Monobromoacetic Acid | 2 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 3/17 | SYR4 |
| Bromate | 1.7 µg/L 17% of the EPA limit 10 µg/L Highest in the city: MODESTO IRRIGATION DISTRICT · 23 people · 2019 | 1/17 | SYR4 |
| Combined Radium (-226 And -228) | 1.183 pCi/L 24% of the EPA limit 5 pCi/L Main supplier: MODESTO, CITY OF · 218,771 people · 2015 | 1/17 | SYR4 |
| Cadmium | 1 µg/L 20% of the EPA limit 5 µg/L Highest in the city: MORNINGSIDE MOBILEHOME PARK · 67 people · 2017 | 1/17 | SYR4 |
| 1,1-Dichloroethylene | 0.7300 µg/L 10% of the EPA limit 7 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 1/17 | SYR4 |
| Ethylbenzene | 0.5200 µg/L 0.1% of the EPA limit 700 µg/L Highest in the city: MODESTO IRRIGATION DISTRICT · 23 people · 2019 | 1/17 | SYR4 |
| 1,2-DIBROMO-3-CHLOROPROPANE | 0.3925 µg/L 196% of the EPA limit, at the 95th percentile of samples — 0.2000 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019 | 6/17 | SYR4 |
| Nitrite | 0.1200 µg/L 0% of the EPA limit 1000 µg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2019
Highest in the city: 0.3360 µg/L — CITY OF MODESTO - GRAYSON · 914 people · 2018 | 5/17 | SYR4 |
| Di(2-ethylhexyl) Phthalate | 0.2000 µg/L 3.3% of the EPA limit 6 µg/L Highest in the city: CITY OF MODESTO - DEL RIO · 1,327 people · 2018 | 1/17 | SYR4 |
| PFOS | 0.0260 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2024 | 1/17 | UCMR-5 |
| Lead | 0.0120 mg/L 80% of the EPA limit 0.0150 mg/L Main supplier: MODESTO, CITY OF · 218,771 people · 2027 | 16/17 | LCR |
| PFHXS | 0.0093 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2024 | 1/17 | UCMR-5 |
| PFOA | 0.0086 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2024 | 1/17 | UCMR-5 |
| Pfpea | 0.0067 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2024 | 1/17 | UCMR-5 |
| Pfhxa | 0.0061 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2024 | 1/17 | UCMR-5 |
| PFBS | 0.0043 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2024 | 1/17 | UCMR-5 |
| Pfhpa | 0.0036 µg/L No EPA limit set Main supplier: MODESTO, CITY OF · 218,771 people · 2024 | 1/17 | 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 Modesto
| Supplier | Population served |
|---|---|
| MODESTO, CITY OF | 218,771 |
| CITY OF MODESTO - SALIDA | 14,537 |
| CITY OF WATERFORD | 8,788 |
| CITY OF MODESTO - DEL RIO | 1,327 |
| CITY OF MODESTO - SOUTH TURLOCK | 1,099 |
| CITY OF MODESTO - GRAYSON | 914 |
| HILLSVIEW HOMES | 887 |
| RIVERDALE PARK TRACT CSD | 610 |
| WATERFORD - HICKMAN | 597 |
| PARK HEIGHTS MUTUAL WATER CO | 250 |
| CITY OF MODESTO - WALNUT MANOR | 175 |
| CITY OF MODESTO - NORTH TURLOCK | 172 |
| CITY OF MODESTO - CENTRAL TURLOCK | 119 |
| MORNINGSIDE MOBILEHOME PARK | 67 |
| COUNTRY WESTERN MHRV | 55 |
| RIVER ROAD MUTUAL WATER COMPANY | 26 |
| MODESTO IRRIGATION DISTRICT | 23 |
Frequently asked questions about Modesto tap water
Is Modesto tap water safe to drink?
EPA testing detected 40 contaminants in the water serving Modesto. 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 Modesto?
17 public water suppliers report drinking-water monitoring for Modesto, California to the EPA. Each is listed above with its population served.
What contaminants are in Modesto's water?
The contaminants EPA monitoring detected in Modesto include Nitrate-Nitrite, Nitrate, Barium, Fluoride, 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.