Sioux City, IA Tap Water Quality 2026

Water quality report for Sioux City, IA — PFAS, lead and copper results, violation history and state inspection findings from EPA SDWIS.

A look at Sioux City's drinking water using EPA enforcement records: violations, lead and copper results, PFAS sampling and state inspection findings.

Main Utility: Sioux City Water Supply PWSID: IA9778054 Updated: 2026 Q2

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PFAS above the federal limit at 1 of 2 sampling points

Lead is 2.00 ppb, 13% of the action level and no violations are open. However, PFAS exceeds the federal limit at 1 of 2 sampling points, running as high as 3.03 times the limit.

Sioux City earns a D for water quality

Graded on violations, lead, and PFAS, with state inspection findings.

Lead: 2.00 ppb — 13% of the federal action level

PFAS above the federal limit at 1 of 2 sampling points

8 violations since 2015, 5 health-based

No violations currently open

Sioux City's lead level vs. all Iowa community water systems

0 ppb5 ppb10 ppb15 ppb

Lead level: 2.00 ppb — 13% of the federal action level

✓ Lower lead than 57% of Iowa utilities

Population Served

83300

~29424 connections

Water Source

Surface water

Groundwater under the direct influence of surface water — SDWIS source code GU

Active Violations

8 since 2015, all resolved

Lead & Copper Testing

Lead (Pb)

90th percentile of tap samples collected across the distribution system

13% of EPA action level

2.00 ppb

Action level: 15 ppb

Copper (Cu)

90th percentile of tap samples. SDWIS reports a copper figure only when a system exceeds the action level, so any value here is an exceedance.

146.2% of EPA action level

1,900 ppb

Action level: 1,300 ppb

The 90th-percentile lead result is 2.00 ppb, 13% of the 15 ppb federal action level. The action level is a treatment trigger, not a legal maximum, and it is measured across sampled taps rather than at any single home. Copper reached the action level here; a copper figure appears in SDWIS only when a system triggers it.

Contaminant Violations (2015–Present)

Contaminant	Type	Measured	Limit	Period	Status
Total Haloacetic Acids (HAA5)	MONITORING AND REPORTING	—	0.060 mg/L	2024	Resolved
TTHM	MONITORING AND REPORTING	—	0.080 mg/L	2024	Resolved
TTHM	MCL EXCEEDANCE	0.084 MG/L	0.080 mg/L	2019	Resolved
TTHM	MCL EXCEEDANCE	0.083 MG/L	0.080 mg/L	2019	Resolved
Epichlorohydrin	TREATMENT TECHNIQUE	—	TT	2017	Resolved
Epichlorohydrin	TREATMENT TECHNIQUE	—	TT	2016	Resolved
Epichlorohydrin	TREATMENT TECHNIQUE	—	TT	2016	Resolved
Interim Enhanced Surface Water Treatment Rule	MONITORING AND REPORTING	—	—	2015	Resolved

Understanding violation types MCL violations mean a contaminant exceeded the federal maximum limit — the most serious type.
TT (Treatment Technique) violations mean required treatment procedures weren't followed, but don't necessarily mean contamination occurred.

Violation History

8 violations are on record since 2015, of which 5 were health-based. All have been resolved and none remain open.

About the Main Water System

Utility Sioux City Water Supply

PWSID IA9778054

Water source Surface water — Groundwater under the direct influence of surface water — SDWIS source code GU

Population served 83,300

Service connections 29,424

Systems serving this area 2

Regulator State primacy agency

Data through 2026 Q2 — EPA SDWIS

Frequently Asked Questions

Is Sioux City tap water safe to drink? ▼

It meets most federal standards, but PFAS exceeds the federal limit at 1 of 2 sampling points. No violations are currently open. Lead is 2.00 ppb, 13% of the action level.

Does Sioux City water have PFAS? ▼

Yes. PFAS exceeds the federal limit at 1 of 2 sampling points, running as high as 3.03 times the limit. Limits are enforced on a running annual average at each sampling point, not on a single sample.

Who supplies water to Sioux City? ▼

Sioux City Water Supply (PWSID IA9778054), one of 2 systems serving this area. Surface water. Groundwater under the direct influence of surface water — SDWIS source code GU

When was this system last inspected? ▼

It was last inspected on 2024-02-05. No significant deficiencies were recorded.

What Should Sioux City Residents Do?

Consider a reverse-osmosis filter

Reverse osmosis removes more than 95% of PFAS. Standard carbon pitchers do not.

Check for a lead service line

Lead reaches tap water mainly through service lines and household plumbing. Suppliers now publish an inventory identifying lead lines.

Flush before drinking

If water has sat in pipes more than six hours, run the cold tap for two minutes before drinking or cooking.

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