Is Sioux City, IA tap water safe?
Supplied by Sioux City Water Supply · serves 85,791 people (29,424 connections) · Groundwater under influence of surface water · EPA ID IA9778054
Data: U.S. EPA · How we read the data · How we check it
Most of Sioux City gets its water from Sioux City Water Supply. Parts of the city are served by a smaller system: Berea Heights Inc (33 people). Your water bill names your system.
Summary
PFAS above the 2024 federal limits. Systems have until 2029 to meet the PFAS limits.
Is it an emergency? No: PFAS limits are about years of exposure, not a glass of water, and nothing in EPA's data calls for you to stop drinking the water today. If your utility ever issues a boil-water or do-not-drink notice, follow it.
- PFAS
- Above limitPFHxS, the PFAS Hazard Index above the federal limit in EPA's 2023–2025 testing (PFHxS 30.3 ppt vs a limit of 10 ppt, where ppt = parts per trillion).
- Lithium
- Above screening levelHighest result 240 ppb. EPA uses 10 ppb to decide what to study further. It is not a health limit, and there is no federal limit for lithium. About 1 in 4 systems tested were above it.
- Lead
- Below action level2 ppb (parts per billion) at the 90th percentile: 9 in 10 homes sampled were at or below it. Action level 15 ppb, falling to 10 ppb in Nov 2027. Monitoring period ending Dec 2025. Your home's pipes can make yours higher.
- Violations
- Resolved5 health-based violations since 2016, most recently Oct 2019.
- Pregnant, or mixing baby formula with tap water? Babies drink more water for their size, so PFAS exposure matters more for them. Consider bottled water or a filter certified for PFAS for formula, and ask your doctor. Health effects.
- To lower your PFAS exposure now, a home filter certified for PFAS reduction works (reverse osmosis, or activated carbon certified to NSF/ANSI 53 or 58). Filters for these results.
- Built before 1986, or not sure what your service line is made of? Check your service line and test your tap. Utility data can't show your pipes.
- Tested your own tap? Compare your result with these numbers. Moving? Compare this system with another.
- Read Sioux City Water Supply's annual water quality report (Consumer Confidence Report). It lists every regulated contaminant tested and is usually on the utility's website or mailed with your bill, and you can also request it at (712) 279-6150. EPA: how to find it.
PFAS (“forever chemicals”)
EPA UCMR 5: 2 entry points tested Oct 2023 to Jul 2024. "Average" is the highest entry-point average (non-detects counted as zero), the way EPA compares UCMR 5 results to the limits. ppt = parts per trillion. These results do not determine compliance.
| Contaminant | Highest average |
|---|---|
| PFOA One sample above limit Limit 4 ppt | 2.85 ppt 71% of the limit |
| PFOS One sample above limit Limit 4 ppt | 2.1 ppt 52% of the limit |
| PFHxS Above limit Limit 10 ppt | 30.3 ppt 3.02× the limit |
| PFNA Not detected Limit 10 ppt | – |
| HFPO-DA (GenX) Not detected Limit 10 ppt | – |
| Hazard Index (a combined score for PFHxS, PFNA, GenX and PFBS, where above 1 is over the limit) Above limit Limit 1 | 3.03 |
| PFBS Detected, below limit Guideline 2,000 ppt | 18 ppt |
| PFBA Detected, below limit Guideline 6,000 ppt | 7.83 ppt |
| PFHxA Detected, below limit Guideline 3,000 ppt | 21.9 ppt |
| PFPeA Detected, no limit | 19 ppt |
| PFHpA Detected, no limit | 3.08 ppt |
| PFPeS Detected, no limit | 11.3 ppt |
For context: the PFHxS average is higher than at 99% of the Iowa systems EPA tested.
29 PFAS tested, 9 detected at least once. "Not detected" means below EPA's reporting limit (about 2 to 20 ppt depending on the chemical), not proven zero. PFAS not listed were not detected. The limits for PFHxS, PFNA, GenX and the Hazard Index were proposed for rescission in May 2026. That proposal is not final. Systems have until 2029 to meet the limits.
Lithium
Detected in 8 of 8 samples. Highest result 240 ppb. EPA's non-enforceable screening level is 10 ppb. Above screening level The screening level is how EPA decides what to study further, not a health limit. There is no federal limit for lithium and no filter is certified to remove it. About lithium.
Lead and copper
Latest 90th percentile: 2 ppb lead (Jan 2023 – Dec 2025). Below action level
Highest since 2016: 5 ppb (Jun 2017).
| Monitoring period | Lead (90th pct.) |
|---|---|
| Jan 2023 – Dec 2025 | 2 ppb |
| Jan 2020 – Dec 2022 | 3 ppb |
| Jan 2019 – Dec 2019 | 2 ppb |
Earlier results (9)
| Jan 2018 – Dec 2018 | 2 ppb |
| Jan 2017 – Jun 2017 | 5 ppb |
| Jul 2016 – Dec 2016 | 2 ppb |
| Jan 2011 – Dec 2013 | 8 ppb |
| Jan 2008 – Dec 2010 | 5 ppb |
| Jan 2005 – Dec 2007 | 3 ppb |
| Jan 2002 – Dec 2004 | 3 ppb |
| Jan 2001 – Dec 2001 | 5 ppb |
| Jan 2000 – Dec 2000 | 6 ppb |
Copper 90th percentile: 1.9 ppm (Dec 1992), action level 1,300 ppb.
Lead comes from pipes and fixtures, not the source water, so it varies home to home. The 90th percentile means 9 in 10 sampled homes were at or below it. More on lead.
Violations
| When | What happened |
|---|---|
| Jul 2019 – Oct 2019 2 times | The running annual average for TTHM was above the legal limit. EPA record: TTHM · Maximum Contaminant Level Violation, Average · measured 0.084 mg/l (limit 0.080 mg/L) Resolved |
| May 2016 – Mar 2017 3 times | A required treatment step was not followed. EPA record: Epichlorohydrin · Treatment Techniques (limit TT ) Resolved |
Health-based violations mean a contaminant exceeded a limit or a required treatment step was missed. Monitoring and reporting violations mean required tests or reports were late or missing, so the water's quality during that time is unknown. The total includes every violation in EPA's records, most of them paperwork.
Earlier EPA testing (2013–2020)
| Contaminant | Highest | Guideline |
|---|---|---|
| Manganese | 12.9 ppb | 300 ppb |
| Vanadium | 0.9 ppb | 21 ppb |
| Cobalt | 1.1 ppb | 70 ppb |
| Strontium | 1.34 ppm | 1.5 ppm |
| Chromium-6 | 0.11 ppb | – |
| Chlorate | 1,130 ppb | 210 ppb |
| Molybdenum | 4.1 ppb | 40 ppb |
| 1,4-Dioxane | 0.73 ppb | 0.35 ppb |
Where it serves
Sioux City
ZIP codes the system reported serving: 51101, 51102, 51103, 51104, 51105, 51106, 51107, 51108, 51111
Nearby utilities
- Council Bluffs Water Works Council Bluffs · 91 mi
- Ames Water Treatment Plant Ames · 145 mi
- West Des Moines Water Works West Des Moines · 148 mi
- City of Ankeny Ankeny · 151 mi
- Des Moines Water Works Des Moines · 155 mi
- Waterloo Water Works Waterloo · 205 mi
Questions
Is Sioux City tap water safe to drink?
Most of Sioux City gets its water from Sioux City Water Supply. Sioux City Water Supply had 5 health-based violations since 2016, all since resolved. EPA testing found PFAS above the 2024 federal limits, which systems must meet by 2029. Federal data can't tell you about your own pipes: lead comes from service lines and plumbing, so test your tap if your home was built before 1986. For the official word, read the utility's annual Consumer Confidence Report.
Does Sioux City water have PFAS?
Yes. EPA's 2023–2025 testing of Sioux City Water Supply found 9 PFAS at least once. The highest entry-point averages were above the federal limit for PFHxS: PFHxS 30.3 ppt (limit 4 ppt for PFOA and PFOS, 10 ppt for the others).
What is the lead level in Sioux City water?
The most recent 90th-percentile lead result for Sioux City Water Supply is 2 ppb, for the period ending Dec 2025. The federal action level is 15 ppb, falling to 10 ppb in November 2027. The 90th percentile means 9 in 10 homes sampled were at or below this number. Individual homes can be higher.
Check these numbers yourself
Every figure on this page comes from public EPA records. You don't have to take our word for it:
- EPA's own report for IA9778054: violations, enforcement and inspections, straight from EPA.
- EPA UCMR 5 data: the PFAS and lithium results (search the file for PWSID IA9778054).
- EPA SDWIS download: the lead results, population and violation records we use.
- The utility's annual water quality report (Consumer Confidence Report): ask Sioux City Water Supply at (712) 279-6150, or see EPA's guide to finding it.
Found something that doesn't match? Tell us and we'll check it against EPA's records. How we check our data.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.