Johnston County, Oklahoma
8 ZIP codes · Avg score 90/100 · Grade A · Updated 2026-06-03
Based on current EPA data, Johnston County's 8 ZIP codes maintain an above-average drinking water safety record.
How Johnston County Compares
How Johnston County Compares
Johnston County scores 11 points above the Oklahoma state average (79/100) and 22 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Johnston County, Oklahoma
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 16.1 (asthma 12.4%, diabetes 15.3%)
Estimated additional annual cost per homeowner: $665, driven primarily by wildfire
Infrastructure: 0.361% avg pipe failure probability, 13% of ZIPs at high risk
58% of homes built before 1978 (lead paint era)
Violation History (2021–2025)
↑ Worsening trendEPA violation counts by year across Johnston County water systems. Health-based shown in red, total in blue.
Peak year: 2024 with 18 violations. Past 5 years: 34 total (34 health-based). Health-based violations are rising versus the prior 2-year window — worth closer monitoring.
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: $665
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
4,571 housing units in Johnston 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 Johnston County
Remediation costs are relatively manageable for most homeowners in Johnston 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 Johnston 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 Johnston County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Johnston Company Rwd #3 | 2,783 | 28 |
| 2 | Tishomingo Municipal Authority | 3,000 | 21 |
| 3 | Murray State College | 1,150 | 21 |
| 4 | Ravia | 459 | 13 |
| 5 | Mannsville Public Works Authority | 587 | 5 |
13 total water systems serve Johnston County.
All ZIP Codes in Johnston County
8 ZIP codes tracked in Johnston County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 73432 | Coleman | 99 | A | 1 | $114K |
| 2 | 73450 | Milburn | 99 | A | 0 | $124K |
| 3 | 73461 | Wapanucka | 99 | A | 1 | $99K |
| 4 | 73455 | Ravia | 98 | A | 13 (1 health) | $69K |
| 5 | 74856 | Mill Creek | 98 | A | 4 (1 health) | $122K |
| 6 | 73447 | Mannsville | 93 | A | 1 | $96K |
| 7 | 73460 | Tishomingo | 70 | B | 21 (13 health) | $142K |
| 8 | 74836 | Connerville | 66 | C | 0 | $210K |
Recommended Buyer Guides for Johnston County
While many sites publish identical guide lists across every county they cover, the selection here changes by location — driven by the EPA, NSF, FEMA, and CDC datasets that describe the actual conditions documented for this jurisdiction in the federal record.
- Best Lead Paint Test Kits — 58% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
- Best HEPA Air Purifiers for Wildfire Smoke — Wildfire is the top compound risk factor
Deep Dive Reports
Detailed analysis for Johnston County, Oklahoma
Overview
Johnston County in Oklahoma covers 8 ZIP codes with an average Home Safety Score of A (90/100).
6 of 8 ZIP codes have recorded EPA violations. 15 health-based violations have been documented.
← Back to Oklahoma 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.