What was found in Sioux City'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 | 2600 µg/L 26% of the EPA limit 10000 µg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Copper | 1200 µg/L 92% of the EPA limit 1300 µg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Fluoride | 660 µg/L 17% of the EPA limit 4000 µg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2014 | 1/2 | SYR4 |
| Lithium | 240 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2024 | 1/2 | UCMR-5 |
| TTHM | 98.95 µg/L 124% of the EPA limit, at the 95th percentile of samples — 80 µg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Chloroform | 63.95 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Total Haloacetic Acids (HAA5) | 43 µg/L 72% of the EPA limit 60 µg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Bromodichloromethane | 27 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Trichloroacetic Acid | 21 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Dichloroacetic Acid | 19 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Lead | 12.95 µg/L 86% of the EPA limit 15 µg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Dibromochloromethane | 12 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Dibromoacetic Acid | 3 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Monochloroacetic Acid | 3 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Toluene | 2.43 µg/L 0.2% of the EPA limit 1000 µg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2018 | 1/2 | SYR4 |
| Arsenic | 2 µg/L 20% of the EPA limit 10 µg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2017 | 1/2 | SYR4 |
| Bromoform | 1.615 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| Carbon Tetrachloride | 1 µg/L 20% of the EPA limit 5 µg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2018 | 1/2 | SYR4 |
| cis-1,2-Dichloroethylene | 0.8300 µg/L 1.2% of the EPA limit 70 µg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2019 | 1/2 | SYR4 |
| PFHXS | 0.0350 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2024 | 1/2 | UCMR-5 |
| Pfhxa | 0.0330 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2024 | 1/2 | UCMR-5 |
| Pfpea | 0.0220 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2024 | 1/2 | UCMR-5 |
| PFBS | 0.0210 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2024 | 1/2 | UCMR-5 |
| Pfpes | 0.0140 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2024 | 1/2 | UCMR-5 |
| Pfba | 0.0092 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2024 | 1/2 | UCMR-5 |
| PFOA | 0.0060 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2024 | 1/2 | UCMR-5 |
| Pfhpa | 0.0048 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2024 | 1/2 | UCMR-5 |
| PFOS | 0.0043 µg/L No EPA limit set Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2024 | 1/2 | UCMR-5 |
| Lead | 0.0020 mg/L 13% of the EPA limit 0.0150 mg/L Main supplier: SIOUX CITY WATER SUPPLY · 85,791 people · 2025 | 2/2 | 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 Sioux City
| Supplier | Population served |
|---|---|
| SIOUX CITY WATER SUPPLY | 85,791 |
| BEREA HEIGHTS INC | 33 |
Frequently asked questions about Sioux City tap water
Is Sioux City tap water safe to drink?
EPA testing detected 29 contaminants in the water serving Sioux City. 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 Sioux City?
2 public water suppliers report drinking-water monitoring for Sioux City, Iowa to the EPA. Each is listed above with its population served.
What contaminants are in Sioux City's water?
The contaminants EPA monitoring detected in Sioux City include Nitrate, Copper, Fluoride, Lithium, 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.