Williamson County, Tennessee
11 ZIP codes · Avg score 52/100 · Grade D · Updated 2026-06-03
State safety rankings put Williamson County near the bottom — 11 ZIP codes, below-average compliance.
How Williamson County Compares
How Williamson County Compares
Williamson County scores 17 points below the Tennessee state average (69/100) and 16 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Williamson County, Tennessee
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 11.3 (asthma 9.8%, diabetes 10%)
Estimated additional annual cost per homeowner: $1,177, driven primarily by flood
Infrastructure: 0.243% avg pipe failure probability
25.9% of homes built before 1978 (lead paint era)
Violation History (2022–2023)
→ Stable trendEPA violation counts by year across Williamson County water systems. Health-based shown in red, total in blue.
Peak year: 2022 with 16 violations. Past 5 years: 24 total (24 health-based).
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: $1,177
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
85,960 housing units in Williamson 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 Williamson County
Remediation costs are relatively manageable for most homeowners in Williamson 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 Williamson 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 Williamson County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Milcrofton Utility District | 38,032 | 44 |
| 2 | FRANKLIN WATER DEPT | 77,222 | 44 |
| 3 | H.b.& T.s. Utility District | 40,094 | 44 |
| 4 | Mallory Valley U.d. | 30,347 | 44 |
| 5 | Brentwood Water Department | 30,493 | 24 |
14 total water systems serve Williamson County.
All ZIP Codes in Williamson County
11 ZIP codes tracked in Williamson County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 37024 | Brentwood | 63 | C | 4 | — |
| 2 | 37135 | Nolensville | 62 | C | 0 | $629K |
| 3 | 37065 | Franklin | 58 | C | 8 (3 health) | — |
| 4 | 37014 | Arrington | 53 | D | 0 | $651K |
| 5 | 37067 | Franklin | 53 | D | 8 (3 health) | $686K |
| 6 | 37179 | Thompsons Station | 53 | D | 0 | $502K |
| 7 | 37027 | Brentwood | 52 | D | 4 | $845K |
| 8 | 37068 | Franklin | 51 | D | 8 (3 health) | — |
| 9 | 37046 | College Grove | 45 | D | 0 | $843K |
| 10 | 37064 | Franklin | 43 | D | 8 (3 health) | $664K |
| 11 | 37069 | Franklin | 43 | D | 8 (3 health) | $713K |
Recommended Buyer Guides for Williamson County
Retailer arrangements don't shape what appears here — the selection logic is independent, filtered against EPA detections and the federal hazard data on file for this county.
- 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
- Best Sump Pumps — Flood is the top compound risk factor
- Best Mold Test Kits — Flood-driven moisture and mold risk
Deep Dive Reports
Detailed analysis for Williamson County, Tennessee
Overview
Williamson County in Tennessee covers 11 ZIP codes with an average Home Safety Score of D (52/100).
7 of 11 ZIP codes have recorded EPA violations. 15 health-based violations have been documented.
← Back to Tennessee 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.
What You Can Do
Williamson County has a grade of D. Here are steps to protect your household.
Test your tap water
Order a certified lab test kit ($20-$50) to check for lead, bacteria, and other contaminants specific to your ZIP code.
Consider a certified water filter
NSF-certified filters can remove most common contaminants. Match the filter to your test results for best protection. Try our filter matcher
Contact your water utility
Request the latest Consumer Confidence Report (CCR) from your water provider. It details exactly what was found in your water supply.