Calhoun County, Iowa
10 ZIP codes · Avg score 60/100 · Grade C · Updated 2026-06-03
Safe water is the norm for most of Calhoun County's 10 ZIP codes — but a notable subset have documented violations that push the grade to the middle tier.
How Calhoun County Compares
How Calhoun County Compares
Calhoun County scores 1 points above the Iowa state average (59/100) and 8 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Calhoun County, Iowa
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 14.2 (asthma 9.8%, diabetes 12.4%)
Estimated additional annual cost per homeowner: $827, driven primarily by energy_code_gap
Infrastructure: 0.535% avg pipe failure probability, 90% of ZIPs at high risk
85.9% of homes built before 1978 (lead paint era)
Violation History (2022–2025)
↓ Improving trendEPA violation counts by year across Calhoun County water systems. Health-based shown in red, total in blue.
Peak year: 2022 with 3 violations. Past 5 years: 7 total (7 health-based). Health-based violations are declining versus the prior 2-year window.
Source: EPA SDWIS historical violations. Data may lag 6–12 months for the most recent year.
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: $827
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
4,872 housing units in Calhoun 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 Calhoun County
Remediation costs are relatively manageable for most homeowners in Calhoun 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 Calhoun 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 Calhoun County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Rockwell City Water Supply | 2,250 | 7 |
| 2 | Manson Water Supply | 1,709 | 6 |
| 3 | Knierim Water Supply | 53 | 5 |
| 4 | Pomeroy Water Supply | 671 | 4 |
| 5 | Xenia Rwd (des Moines) | 12,860 | 3 |
12 total water systems serve Calhoun County.
All ZIP Codes in Calhoun County
10 ZIP codes tracked in Calhoun County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 50538 | Farnhamville | 66 | C | 0 | $71K |
| 2 | 50551 | Jolley | 66 | C | 0 | $51K |
| 3 | 51449 | Lake City | 66 | C | 1 | $119K |
| 4 | 51453 | Lohrville | 66 | C | 0 | $56K |
| 5 | 50575 | Pomeroy | 65 | C | 4 (1 health) | $77K |
| 6 | 50579 | Rockwell City | 65 | C | 3 | $137K |
| 7 | 50563 | Manson | 61 | C | 2 | $157K |
| 8 | 50552 | Knierim | 60 | C | 5 (5 health) | — |
| 9 | 50586 | Somers | 44 | D | 2 | $108K |
| 10 | 50520 | Bradgate | 40 | D | 0 | $47K |
Recommended Buyer Guides for Calhoun County
Where county records show a lead exceedance or pre-1978 housing concentration, lead-specific filters and test kits move toward the top of the list.
- Best Lead Paint Test Kits — 85.9% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
- Best Radon Test Kits — EPA Radon Zone 1 (highest risk) dominant in county
Deep Dive Reports
Detailed analysis for Calhoun County, Iowa
Overview
Calhoun County in Iowa covers 10 ZIP codes with an average Home Safety Score of C (60/100).
6 of 10 ZIP codes have recorded EPA violations. 6 health-based violations have been documented.
← 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.