Sioux City Water Supply
Sioux City, Iowa · PWSID: IA9778054
Sioux City Water Quality Summary
Sioux City Water Supply supplies drinking water to about 85,791 people in Sioux City, Iowa, and draws from ground water (wells or aquifers), which is naturally filtered but can carry minerals and contaminants from the surrounding geology. On the IsWaterSafe scale it earns a failing Water Safety Score of 40 out of 100 (Grade F), a composite of its EPA SDWIS violation and contaminant record.
EPA records show 10 health-based violations for this system. A health-based violation means a contaminant exceeded its legal EPA limit, the most serious category in the Safe Drinking Water Act. The system has 28 enforcement actions on file in response.
Across the 2 substances sampled, none exceeded its EPA limit. Haloacetic Acids (HAA5) sits highest relative to its ceiling, detected at 30 ppb against an MCL of 60 ppb (sampled May 2024) — within the legal limit.
The most recent documented episode is a treatment technique violation involving Haloacetic Acids (HAA5), beginning May 2024 and marked resolved August 2024.
Track Sioux City Water Supply
Subscribe for WaterSafety updates by email. No spam, unsubscribe anytime.
Detected Contaminants
| Contaminant | Detected Level | MCL (Limit) | Status | Sample Date |
|---|---|---|---|---|
| Haloacetic Acids (HAA5) | 30 ppb | 60 ppb | Within Limit | May 1, 2024 |
| Total Trihalomethanes | 40 ppb | 80 ppb | Within Limit | May 1, 2024 |
Violation History
Frequently Asked Questions
Sioux City Water Supply has a Water Safety Score of F (40/100). The system serves 85,791 people and has 10 health violations on record. Check the contaminant table above for specific detected substances.
Sioux City Water Supply has 0 contaminant exceedances above EPA health guidelines. See the full contaminant detection table above for all tested substances and their levels relative to legal limits and health guidelines.
The Water Safety Score (0-100, grades A through F) is based on contaminant levels relative to legal limits, health guideline exceedances, violation history, and enforcement actions. Higher scores indicate fewer concerns.
If your water system has violations, request the Consumer Confidence Report from your utility, consider getting an independent water test from a certified lab, and look into certified water filters for specific contaminants of concern. For lead, run cold water for 30 seconds before drinking.
Water quality data sourced from EPA's Safe Drinking Water Information System (SDWIS). Safety scores are calculated based on contaminant levels, violations, and enforcement history. This is not a substitute for your utility's official Consumer Confidence Report.
Source: EPA Ground Water and Drinking Water, 2026.