F0/100
SIOUX CITY WATER SUPPLY — Water Quality Report 2026
Serving 85,791 people · Iowa
Water Source
Groundwater Under Influence of Surface Water
County
—
System ID
IA9778054
Violations
34
Contaminant Test Results
4 contaminants above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 1.90 mg/L | 1.30 mg/L | Over Limit |
PFHxS | 0.029 µg/L | 0.010 µg/L | Over Limit |
chlorate | 1130.00 µg/L | — | Above Goal |
Lead (90th percentile) | 0.002 mg/L | 0.015 mg/L | Above Goal |
EPA Violation History
2
Violations (last 5yr)
0
Unresolved
0
Health-Related
TIER 3Resolved
Failed Level 2 Assessment under Revised Total Coliform Rule
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: May 1, 2024 – May 31, 2024Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
TIER 3Resolved
Failed Level 2 Assessment under Revised Total Coliform Rule
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: May 1, 2024 – May 31, 2024Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Frequently Asked Questions About SIOUX CITY WATER SUPPLY
Is SIOUX CITY WATER SUPPLY water safe to drink?
SIOUX CITY WATER SUPPLY water receives a grade of F (0/100), which is considered failing. 2 contaminant(s) exceed EPA legal limits and 34 violation(s) are on record. Customers may want to consider using a water filter.
What contaminants has SIOUX CITY WATER SUPPLY detected?
70 contaminants were tested in SIOUX CITY WATER SUPPLY's water. Notable contaminants include PFHxS, Copper (90th percentile), Lead (90th percentile), chlorate. 2 exceed EPA legal limits (MCLs). 4 exceed EPA health goals (MCLGs).
Does SIOUX CITY WATER SUPPLY have any EPA violations?
Yes, SIOUX CITY WATER SUPPLY has 34 EPA violation(s) on record, with the most recent in 2024. Violation types include MR, MCL, TT. 14 are health-based violations.
How many people does SIOUX CITY WATER SUPPLY serve?
SIOUX CITY WATER SUPPLY serves approximately 85,791 people, Iowa. The system provides water to 1 community: Sioux City.
What type of water does SIOUX CITY WATER SUPPLY provide?
SIOUX CITY WATER SUPPLY sources its water from groundwater under influence of surface water. Surface water comes from rivers, lakes, or reservoirs and typically requires more extensive treatment. The utility's system ID is IA9778054.
How does SIOUX CITY WATER SUPPLY compare to other utilities in Iowa?
SIOUX CITY WATER SUPPLY scores 0/100 with a grade of F (failing). This score suggests significant water quality concerns relative to other utilities. Visit our Iowa state page for a full comparison of water systems.