Is Oswego, IL Tap Water Safe? Quality & Contaminants

What was found in Oswego'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
Fluoride	1206 µg/L 30% of the EPA limit 4000 µg/L Main supplier: OSWEGO · 38,169 people · 2018	1/1	SYR4
Copper	1043.5 µg/L 80% of the EPA limit 1300 µg/L Main supplier: OSWEGO · 38,169 people · 2017	1/1	SYR4
Nitrate	190 µg/L 1.9% of the EPA limit 10000 µg/L Main supplier: OSWEGO · 38,169 people · 2019	1/1	SYR4
Nitrate-Nitrite	140.2 µg/L 1.4% of the EPA limit 10000 µg/L Main supplier: OSWEGO · 38,169 people · 2016	1/1	SYR4
Lithium	114 µg/L No EPA limit set Main supplier: OSWEGO · 38,169 people · 2025	1/1	UCMR-5
Barium	79.9 µg/L 4% of the EPA limit 2000 µg/L Main supplier: OSWEGO · 38,169 people · 2018	1/1	SYR4
Nitrite	64.65 µg/L 6.5% of the EPA limit 1000 µg/L Main supplier: OSWEGO · 38,169 people · 2019	1/1	SYR4
Lead	11.81 µg/L 79% of the EPA limit 15 µg/L Main supplier: OSWEGO · 38,169 people · 2017	1/1	SYR4
Combined Radium (-226 And -228)	6.6895 pCi/L 134% of the EPA limit, at the 95th percentile of samples — 5 pCi/L Main supplier: OSWEGO · 38,169 people · 2019	1/1	SYR4
Dichloroacetic Acid	2.31475 µg/L No EPA limit set Main supplier: OSWEGO · 38,169 people · 2019	1/1	SYR4
Total Haloacetic Acids (HAA5)	2.2131 µg/L 3.7% of the EPA limit 60 µg/L Main supplier: OSWEGO · 38,169 people · 2019	1/1	SYR4
Xylenes, Total	1.898 µg/L 0% of the EPA limit 10000 µg/L Main supplier: OSWEGO · 38,169 people · 2015	1/1	SYR4
Dichloromethane	0.7895 µg/L 16% of the EPA limit 5 µg/L Main supplier: OSWEGO · 38,169 people · 2015	1/1	SYR4
Mercury	0.1830 µg/L 9.2% of the EPA limit 2 µg/L Main supplier: OSWEGO · 38,169 people · 2018	1/1	SYR4
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: OSWEGO · 38,169 people · 2025	1/1	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 Oswego

Supplier	Population served
OSWEGO	38,169

Frequently asked questions about Oswego tap water

Is Oswego tap water safe to drink?

EPA testing detected 15 contaminants in the water serving Oswego. 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 Oswego?

1 public water supplier report drinking-water monitoring for Oswego, Illinois to the EPA. Each is listed above with its population served.

What contaminants are in Oswego's water?

The contaminants EPA monitoring detected in Oswego include Fluoride, Copper, Nitrate, Nitrate-Nitrite, Lithium. 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.