Is Oakdale, CA Tap Water Safe? Quality & Contaminants

What was found in Oakdale'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	176560 µg/L 1766% of the EPA limit, at the 95th percentile of samples — 10000 µg/L Main supplier: OAKDALE, CITY OF · 23,235 people · 2019 Highest in the city: 651500 µg/L — OID #46 - SUNSET OAKS · 269 people · 2017	11/11	SYR4
Nitrate	6435.35 µg/L 64% of the EPA limit 10000 µg/L Main supplier: OAKDALE, CITY OF · 23,235 people · 2019 Highest in the city: 8305 µg/L — LONE PINE MHP · 64 people · 2019	11/11	SYR4
Fluoride	100 µg/L 2.5% of the EPA limit 4000 µg/L Main supplier: OAKDALE, CITY OF · 23,235 people · 2019 Highest in the city: 195 µg/L — TWIN CYPRESS MOBILE HOME PARK · 112 people · 2017	8/11	SYR4
Barium	148 µg/L 7.4% of the EPA limit 2000 µg/L Main supplier: OAKDALE, CITY OF · 23,235 people · 2019 Highest in the city: 174.2 µg/L — NORTH OAKS MUTUAL WATER CO · 234 people · 2018	7/11	SYR4
Lead	11 µg/L 73% of the EPA limit 15 µg/L Highest in the city: OID-OAKDALE RURAL WATER SYSTEM #1 · 1,570 people · 2017	2/11	SYR4
Arsenic	2.875 µg/L 29% of the EPA limit 10 µg/L Main supplier: OAKDALE, CITY OF · 23,235 people · 2019 Highest in the city: 5.875 µg/L — TWIN CYPRESS MOBILE HOME PARK · 112 people · 2017	6/11	SYR4
Tetrachloroethylene	4.44 µg/L 89% of the EPA limit 5 µg/L Main supplier: OAKDALE, CITY OF · 23,235 people · 2019	1/11	SYR4
TTHM	2.75 µg/L 3.4% of the EPA limit 80 µg/L Main supplier: OAKDALE, CITY OF · 23,235 people · 2019	1/11	SYR4
Combined Uranium	2.34675 µg/L 7.8% of the EPA limit 30 µg/L Main supplier: OAKDALE, CITY OF · 23,235 people · 2019	1/11	SYR4
Bromoform	1.485 µg/L No EPA limit set Main supplier: OAKDALE, CITY OF · 23,235 people · 2019	1/11	SYR4
Dibromochloromethane	1.195 µg/L No EPA limit set Main supplier: OAKDALE, CITY OF · 23,235 people · 2019	1/11	SYR4
Carbon Tetrachloride	0.7175 µg/L 14% of the EPA limit 5 µg/L Highest in the city: OID #45 · 144 people · 2019	1/11	SYR4
1,2-DIBROMO-3-CHLOROPROPANE	0.2800 µg/L 140% of the EPA limit, at the 95th percentile of samples — 0.2000 µg/L Highest in the city: TULLY MOBILE ESTATES · 56 people · 2019	1/11	SYR4
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: OAKDALE, CITY OF · 23,235 people · 2025 Highest in the city: 0.0042 mg/L — 4N MOBILEHOME PARK · 65 people · 2024	11/11	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 Oakdale

Supplier	Population served
OAKDALE, CITY OF	23,235
OID-OAKDALE RURAL WATER SYSTEM #1	1,570
OID #51 - SUNSET OAKS #10	287
OID #46 - SUNSET OAKS	269
NORTH OAKS MUTUAL WATER CO	234
OID #22 - WILLIAMS TRACT	150
OID #45	144
TWIN CYPRESS MOBILE HOME PARK	112
4N MOBILEHOME PARK	65
LONE PINE MHP	64
TULLY MOBILE ESTATES	56

Frequently asked questions about Oakdale tap water

Is Oakdale tap water safe to drink?

EPA testing detected 14 contaminants in the water serving Oakdale. 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 Oakdale?

11 public water suppliers report drinking-water monitoring for Oakdale, California to the EPA. Each is listed above with its population served.

What contaminants are in Oakdale's water?

The contaminants EPA monitoring detected in Oakdale include Nitrate-Nitrite, Nitrate, Fluoride, Barium, Lead. 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.