What was found in Iowa 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 | 6200 µg/L 62% of the EPA limit 10000 µg/L Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2019
Highest in the city: 8700 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 4/31 | SYR4 |
| Copper | 20 µg/L 1.5% of the EPA limit 1300 µg/L Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2017
Highest in the city: 2215 µg/L — MAKADA HOMEOWNERS ASSOCIATION · 85 people · 2017 | 30/31 | SYR4 |
| Fluoride | 610 µg/L 15% of the EPA limit 4000 µg/L Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2014
Highest in the city: 790 µg/L — KESSLERS HOMEOWNERS ASSN · 60 people · 2013 | 29/31 | SYR4 |
| Barium | 420 µg/L 21% of the EPA limit 2000 µg/L Highest in the city: FAR HORIZONS SUBDIVISION · 80 people · 2013 | 14/31 | SYR4 |
| TTHM | 58.95 µg/L 74% of the EPA limit 80 µg/L Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2019
Highest in the city: 100 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 7/31 | SYR4 |
| Chloroform | 36.95 µg/L No EPA limit set Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2019
Highest in the city: 78 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 8/31 | SYR4 |
| Lithium | 47 µg/L No EPA limit set Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2023
Highest in the city: 72 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2024 | 3/31 | UCMR-5 |
| Total Haloacetic Acids (HAA5) | 16 µg/L 27% of the EPA limit 60 µg/L Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2019
Highest in the city: 38 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 5/31 | SYR4 |
| Dichloroacetic Acid | 10 µg/L No EPA limit set Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2019
Highest in the city: 29 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 6/31 | SYR4 |
| Lead | 13.7 µg/L 91% of the EPA limit 15 µg/L Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2017
Highest in the city: 26.5 µg/L — WOODLAND HEIGHTS HOMEOWNERS ASSOC. · 41 people · 2018 | 29/31 | SYR4 |
| Bromodichloromethane | 15 µg/L No EPA limit set Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2019
Highest in the city: 23.3 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 6/31 | SYR4 |
| Dibromochloromethane | 9.695 µg/L No EPA limit set Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2019
Highest in the city: 17.65 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 6/31 | SYR4 |
| Gross Alpha, Excl. Radon And U | 17 pCi/L 113% of the EPA limit, at the 95th percentile of samples — 15 pCi/L Highest in the city: IOWA CITY REGENCY MOBILE HOME COMMUNITY · 225 people · 2015 | 1/31 | SYR4 |
| Xylenes, Total | 11.04 µg/L 0.1% of the EPA limit 10000 µg/L Highest in the city: UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 2/31 | SYR4 |
| Combined Radium (-226 And -228) | 6.4 pCi/L 128% of the EPA limit, at the 95th percentile of samples — 5 pCi/L Highest in the city: IOWA CITY REGENCY MOBILE HOME COMMUNITY · 225 people · 2019 | 23/31 | SYR4 |
| Trichloroacetic Acid | 3.85 µg/L No EPA limit set Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2019
Highest in the city: 5.2 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 5/31 | SYR4 |
| Bromoform | 2.1 µg/L No EPA limit set Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2019
Highest in the city: 4.795 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 3/31 | SYR4 |
| Di(2-ethylhexyl) Phthalate | 4.1 µg/L 68% of the EPA limit 6 µg/L Highest in the city: RAPID CREEK RIDGE · 70 people · 2019 | 5/31 | SYR4 |
| Dibromoacetic Acid | 3 µg/L No EPA limit set Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2019
Highest in the city: 4 µg/L — UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 3/31 | SYR4 |
| Monochloroacetic Acid | 4 µg/L No EPA limit set Highest in the city: UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 1/31 | SYR4 |
| Di(2-ethylhexyl) Adipate | 3.8 µg/L 1% of the EPA limit 400 µg/L Highest in the city: RAPID CREEK RIDGE · 70 people · 2019 | 1/31 | SYR4 |
| Combined Uranium | 2.2 µg/L 7.3% of the EPA limit 30 µg/L Highest in the city: IOWA CITY REGENCY MOBILE HOME COMMUNITY · 225 people · 2015 | 1/31 | SYR4 |
| Arsenic | 2 µg/L 20% of the EPA limit 10 µg/L Highest in the city: LAKE RIDGE, INCORPORATED · 1,300 people · 2016 | 3/31 | SYR4 |
| Toluene | 2 µg/L 0.2% of the EPA limit 1000 µg/L Highest in the city: IOWA CITY MHP LLC · 280 people · 2019 | 1/31 | SYR4 |
| Atrazine | 1.82 µg/L 61% of the EPA limit 3 µg/L Highest in the city: UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 1/31 | SYR4 |
| Ethylbenzene | 1.76 µg/L 0.3% of the EPA limit 700 µg/L Highest in the city: UNIVERSITY WATER SYSTEM · 26,684 people · 2019 | 1/31 | SYR4 |
| 2,4-D | 0.8000 µg/L 1.1% of the EPA limit 70 µg/L Highest in the city: FAR HORIZONS SUBDIVISION · 80 people · 2019 | 1/31 | SYR4 |
| Lead | 0.0040 mg/L 27% of the EPA limit 0.0150 mg/L Main supplier: IOWA CITY WATER DEPARTMENT · 68,753 people · 2023 | 31/31 | 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 Iowa City
Frequently asked questions about Iowa City tap water
Is Iowa City tap water safe to drink?
EPA testing detected 28 contaminants in the water serving Iowa 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 Iowa City?
31 public water suppliers report drinking-water monitoring for Iowa City, Iowa to the EPA. Each is listed above with its population served.
What contaminants are in Iowa City's water?
The contaminants EPA monitoring detected in Iowa City include Nitrate, Copper, Fluoride, Barium, 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.