Sioux County, Iowa
12 ZIP codes · Avg score 67/100 · Grade C · Updated 2026-06-03
Water monitoring across Sioux County's 12 ZIP codes paints a mid-range picture — solid compliance in some zones, documented concerns in others; most violations on record are concentrated in specific prior years rather than spread evenly across the full compliance history, and the overall county grade has held steady in the middle tier without major shifts in either direction.
How Sioux County Compares
How Sioux County Compares
Sioux County scores 8 points above the Iowa state average (59/100) and 1 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Sioux County, Iowa
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 11.9 (asthma 9.6%, diabetes 9.8%)
Estimated additional annual cost per homeowner: $809, driven primarily by water_lead
Infrastructure: 0.46% avg pipe failure probability, 83% of ZIPs at high risk
74.9% of homes built before 1978 (lead paint era)
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $809
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
13,094 housing units in Sioux County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Sioux County
Remediation costs are relatively manageable for most homeowners in Sioux County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for Sioux County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 5 systems in Sioux County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Rock Valley Water Supply | 4,059 | 2 |
| 2 | Rock Valley Rural Water District | 2,230 | 2 |
| 3 | Hull Water Supply | 2,384 | 1 |
| 4 | Rural Water System #1 | 3,428 | 1 |
| 5 | Hospers Municipal Water Department | 718 | 1 |
16 total water systems serve Sioux County.
All ZIP Codes in Sioux County
12 ZIP codes tracked in Sioux County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 51003 | Alton | 70 | B | 0 | $226K |
| 2 | 51023 | Hawarden | 70 | B | 0 | $149K |
| 3 | 51041 | Orange City | 70 | B | 0 | $254K |
| 4 | 51234 | Boyden | 70 | B | 0 | $208K |
| 5 | 51250 | Sioux Center | 70 | B | 1 | $286K |
| 6 | 51022 | Granville | 66 | C | 0 | $169K |
| 7 | 51027 | Ireton | 66 | C | 0 | $219K |
| 8 | 51036 | Maurice | 66 | C | 0 | $242K |
| 9 | 51238 | Hospers | 66 | C | 1 | $176K |
| 10 | 51239 | Hull | 66 | C | 0 | $231K |
| 11 | 51244 | Matlock | 66 | C | 1 | $90K |
| 12 | 51247 | Rock Valley | 63 | C | 1 | $238K |
Recommended Buyer Guides for Sioux County
Editorial-only picks, screened against the EPA detections on file.
- Best Lead Paint Test Kits — 74.9% of homes built before 1978
- Best Radon Test Kits — EPA Radon Zone 1 (highest risk) dominant in county
Deep Dive Reports
Detailed analysis for Sioux County, Iowa
Overview
Sioux County in Iowa covers 12 ZIP codes with an average Home Safety Score of C (67/100).
4 of 12 ZIP codes have recorded EPA violations. All violations are monitoring/reporting type.
← Back to Iowa water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.