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Community Water System · PWS IA9778054

Sioux City Water Supply

Sioux City, Iowa 51103 - drinking water served from surface water sources to 85,791 people, tracked in EPA SDWIS and UCMR5.

85,791
People served
133
EPA violations
54
Health-based
9 PFAS
UCMR5 result

The verdict

EPA records 133 drinking-water violations at Sioux City Water Supply, 41% of them health-based - above the Iowa per-system average, and UCMR5 testing detected 9 PFAS compounds.

133
Total EPA violations on record
41%
Health-based (MCL / treatment failure)
85,791
People served by this system
9
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Sioux City Water Supply

Sioux City Water Supply is a local-owned community water system that delivers drinking water to 85,791 residents in Sioux City, Iowa (Woodbury County) through 29,424 service connections. Its water is drawn from surface water sources. EPA's Safe Drinking Water Information System records 133 total violations for this system , of which 54 (41%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 54 monitoring and reporting violations are on file. The most recent violation on record dates to 2024.

The most frequently cited contaminant at this system is Coliform (TCR), recorded in 17 violations (MCL, health-based). Under EPA's UCMR5 PFAS monitoring program, 9 PFAS compounds were detected in samples collected from this system, with a maximum reported concentration of 35 ppt (parts per trillion). PFAS are persistent synthetic chemicals linked to health effects at very low exposure levels.

Across Iowa, EPA tracks 1,795 public water systems serving 3,114,444 people, with 138,271 cumulative violations and 27,946 health-based violations on record. About 95% of systems in the state carry at least one violation, and state-wide the average per system is 77 violations. Statewide, 127 of 152 UCMR5-tested systems have reported PFAS detections (83.6%).

Sioux City Water Supply's 133 violations sit above the Iowa average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

PFAS Detected

9 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.

Population Served
85,791
Total Violations
133
Health-Based Violations
54
Water Source
Surface Water

System Details

System Type
Community
Owner Type
Local
Connections
29,424
County
Woodbury
School/Daycare
No
MCL Violations
28
Monitoring Violations
54
Treatment Tech Violations
26

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Coliform (TCR) MCL 17 1997
Epichlorohydrin TT 10 2017
TTHM MCL 9 2019
Surface Water Treatment Rule TT 8 2012
Interim Enhanced Surface Water Treatment Rule TT 8 2004
Surface Water Treatment Rule MR 7 2012
Gross Alpha, Excl. Radon and U MR 4 1993
Nitrate MR 4 2007
Interim Enhanced Surface Water Treatment Rule MR 4 2015
TTHM MR 4 2024
Total Haloacetic Acids (HAA5) MR 4 2024
Barium MR 3 2001
Chromium MR 3 2001
Fluoride MR 3 2001
Antimony, Total MR 3 2001
Selenium MR 3 2001
Arsenic MR 3 2001
Cadmium MR 3 2001
Mercury MR 3 2001
Thallium, Total MR 3 2001
Combined Radium (-226 and -228) MCL 2 1979

PFAS Testing Results (UCMR5)

Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 31 of 232 samples detected PFAS.

Contaminant Date Result MRL Status
ADONA 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFNA 7/15/2024 <4.00 ppt 4.00 ppt Not Detected
PFMBA 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFEESA 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
NFDHA 7/15/2024 <20.00 ppt 20.00 ppt Not Detected
PFTA 7/15/2024 <8.00 ppt 8.00 ppt Not Detected
NMeFOSAA 7/15/2024 <6.00 ppt 6.00 ppt Not Detected
NEtFOSAA 7/15/2024 <5.00 ppt 5.00 ppt Not Detected
PFTrDA 7/15/2024 <7.00 ppt 7.00 ppt Not Detected
PFPeS 7/15/2024 <4.00 ppt 4.00 ppt Not Detected
PFHpS 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFBS 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFHpA 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFBA 7/15/2024 <5.00 ppt 5.00 ppt Not Detected
4:2 FTS 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
6:2 FTS 7/15/2024 <5.00 ppt 5.00 ppt Not Detected
PFOS 7/15/2024 <4.00 ppt 4.00 ppt Not Detected
PFOA 7/15/2024 <4.00 ppt 4.00 ppt Not Detected
PFDA 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFDoA 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFHxA 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFUnA 7/15/2024 <2.00 ppt 2.00 ppt Not Detected
11Cl-PF3OUdS 7/15/2024 <5.00 ppt 5.00 ppt Not Detected
PFMPA 7/15/2024 <4.00 ppt 4.00 ppt Not Detected
9Cl-PF3ONS 7/15/2024 <2.00 ppt 2.00 ppt Not Detected
8:2 FTS 7/15/2024 <5.00 ppt 5.00 ppt Not Detected
PFPeA 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
HFPO-DA 7/15/2024 <5.00 ppt 5.00 ppt Not Detected
PFHxS 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFBA 7/15/2024 9.20 ppt 5.00 ppt Detected
PFMBA 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFPeA 7/15/2024 18.00 ppt 3.00 ppt Detected
PFEESA 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFHxS 7/15/2024 29.00 ppt 3.00 ppt Detected
6:2 FTS 7/15/2024 <5.00 ppt 5.00 ppt Not Detected
PFMPA 7/15/2024 <4.00 ppt 4.00 ppt Not Detected
PFTA 7/15/2024 <8.00 ppt 8.00 ppt Not Detected
PFTrDA 7/15/2024 <7.00 ppt 7.00 ppt Not Detected
PFHpA 7/15/2024 4.30 ppt 3.00 ppt Detected
PFBS 7/15/2024 17.00 ppt 3.00 ppt Detected
NMeFOSAA 7/15/2024 <6.00 ppt 6.00 ppt Not Detected
NEtFOSAA 7/15/2024 <5.00 ppt 5.00 ppt Not Detected
8:2 FTS 7/15/2024 <5.00 ppt 5.00 ppt Not Detected
NFDHA 7/15/2024 <20.00 ppt 20.00 ppt Not Detected
4:2 FTS 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
PFUnA 7/15/2024 <2.00 ppt 2.00 ppt Not Detected
PFNA 7/15/2024 <4.00 ppt 4.00 ppt Not Detected
PFPeS 7/15/2024 11.00 ppt 4.00 ppt Detected
PFHpS 7/15/2024 <3.00 ppt 3.00 ppt Not Detected
HFPO-DA 7/15/2024 <5.00 ppt 5.00 ppt Not Detected

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Sioux City Water Supply.

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID IA9778054 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Iowa Drinking Water Authority

Iowa's primacy agency administers the Safe Drinking Water Act locally. Search EPA SDWIS for the current state contact, or use the state's public health or environment department portal.

Find IA regulator via EPA SDWIS

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2024 TTHM MR 4 SDWIS / IA9778054 / 2950
2024 Total Haloacetic Acids (HAA5) MR 4 SDWIS / IA9778054 / 2456
2019 TTHM MCL 9 SDWIS / IA9778054 / 2950
2017 Epichlorohydrin TT 10 SDWIS / IA9778054 / 2257
2015 Interim Enhanced Surface Water Treatment Rule MR 4 SDWIS / IA9778054 / 0300
2012 Surface Water Treatment Rule TT 8 SDWIS / IA9778054 / 0200
2012 Surface Water Treatment Rule MR 7 SDWIS / IA9778054 / 0200
2007 Nitrate MR 4 SDWIS / IA9778054 / 1040
2004 Interim Enhanced Surface Water Treatment Rule TT 8 SDWIS / IA9778054 / 0300
2001 Barium MR 3 SDWIS / IA9778054 / 1010
2001 Chromium MR 3 SDWIS / IA9778054 / 1020
2001 Fluoride MR 3 SDWIS / IA9778054 / 1025
2001 Antimony, Total MR 3 SDWIS / IA9778054 / 1074
2001 Selenium MR 3 SDWIS / IA9778054 / 1045
2001 Arsenic MR 3 SDWIS / IA9778054 / 1005

How Sioux City Water Supply Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Sioux City Water Supply Iowa avg Federal benchmark
Total violations 133 77 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 54 15.6 Indicates a contaminant exceeded a federal MCL
PFAS detection 9 compounds 83.6% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 85,791 1,735 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 1,795 regulated public water systems in Iowa.

Federal MCL reference, Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Sioux City Water Supply water safe to drink? ▼
Sioux City Water Supply (PWS ID: IA9778054) has 133 recorded violations in the EPA SDWIS database. PFAS contamination has been detected in UCMR5 testing, with 9 PFAS compounds found. This system serves 85,791 people using Surface Water sources.
How many people does Sioux City Water Supply serve? ▼
Sioux City Water Supply serves 85,791 people in Sioux City, Iowa. It is a Local-owned system using Surface Water water sources with 29,424 service connections.
What type of violations does Sioux City Water Supply have? ▼
Sioux City Water Supply has 133 total violations: 54 health-based violations (MCL exceedances or treatment failures), 54 monitoring/reporting violations, and 26 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Sioux City Water Supply water? ▼
Yes. UCMR5 testing detected 9 PFAS compounds in Sioux City Water Supply's water supply: PFBA, PFPeA, PFHxS, PFHpA, PFBS, and others. PFAS are persistent "forever chemicals" that do not break down in the environment.
What water source does Sioux City Water Supply use? ▼
Sioux City Water Supply uses Surface Water as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. PFAS data from EPA UCMR5 monitoring program (2023-2025). This data is provided for informational purposes only.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.