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Updated 2026-10-15
County water report

Williamson County Water Quality: 3 Cities Ranked by the Records

Williamson County, Tennessee: 3 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.

Find my systemOpen on the mapPrivate wells in Williamson County
Across the county's systems

Highest result for each contaminant

One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.

Perfluorooctanoic acid (PFOA)Detected in 1 system of 3 tested4.0 ng/L federal MCL (2024) · US EPAHighest8.1 ng/L
Lead (90th percentile)Detected in 3 systems15 µg/L federal action level · US EPAHighest6.17 µg/L
Perfluorobutanesulfonic acid (PFBS)Detected in 1 system of 3 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest30.7 ng/L
Perfluorohexanoic acid (PFHxA)Detected in 1 system of 3 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest28.3 ng/L
Perfluorobutanoic acid (PFBA)Detected in 2 systems of 3 testedNo federal or state limit; shown for transparencyHighest11.7 ng/L
Perfluoroheptanoic acid (PFHpA)Detected in 1 system of 3 testedNo federal or state limit; shown for transparencyHighest3.1 ng/L
Perfluoropentanoic acid (PFPeA)Detected in 1 system of 3 testedNo federal or state limit; shown for transparencyHighest14.5 ng/L
24 substances tested, none detected in any systemShow

Tested in these 3 systems: BRENTWOOD WATER DEPARTMENT, FRANKLIN WATER DEPT, NOLENSVILLE-COLLEGE GROVE U.D.

  • 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
  • 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
  • 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
  • 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
  • 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
  • 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
  • Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
  • Lithium
  • N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
  • N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
  • Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
  • Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
  • Perfluoro-3-methoxypropanoic acid (PFMPA)
  • Perfluoro-4-methoxybutanoic acid (PFMBA)
  • Perfluorodecanoic acid (PFDA)
  • Perfluorododecanoic acid (PFDoA)
  • Perfluoroheptanesulfonic acid (PFHpS)
  • Perfluorohexanesulfonic acid (PFHxS)
  • Perfluorononanoic acid (PFNA)
  • Perfluorooctanesulfonic acid (PFOS)
  • Perfluoropentanesulfonic acid (PFPeS)
  • Perfluorotetradecanoic acid (PFTA)
  • Perfluorotridecanoic acid (PFTrDA)
  • Perfluoroundecanoic acid (PFUnA)
3 cities

Cities ranked by the records

Showing 3 of 3 cities · scores are system-level, not tap tests

Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.

PFAS in Williamson County1 of 3 city reports had a PFAS sample above a 2024 EPA limit
4.0 ng/L federal MCL · PFOS, ng/LPFAS in Tennessee
Lead

0of 3 cities above the 15 µg/L action level

Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.

Lead in Tennessee
Who supplies the county

Largest water systems

  1. FranklinFRANKLIN WATER DEPT · TN0000246
    77,222 served
  2. NolensvilleNOLENSVILLE-COLLEGE GROVE U.D. · TN0000511
    34,159 served
  3. BrentwoodBRENTWOOD WATER DEPARTMENT · TN0000069
    30,645 served
Questions

Frequently asked

How does Williamson County tap water compare across cities?

PurityMap ranks 3 cities in Williamson County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Brentwood's main water system: BRENTWOOD WATER DEPARTMENT · PWSID TN0000069 · Purity Score 99 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.

How many Williamson County cities had a PFAS sample above a 2024 EPA limit?

1 of 3 Williamson County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Nolensville (PFOA 8.1 ng/L). That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. PFAS were detected at any level in 2.

Is there lead in Williamson County tap water?

Utilities report lead as a 90th-percentile result from home taps. 3 of 3 Williamson County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.

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