Montgomery County, TX
drinking water quality
749,613 residents · 467 public water systems · 22 ZIP codes
EPA sampled 44 of 467 public water systems here, together serving about 479,423 people. The highest reading was PFOA at 4.8 ng/L at Montgomery Trace Water System. 1 of the sampled system was above a federal limit. Last sampled 9/9/2025.
What was found
| Compound | Highest result | Federal limit | Ratio |
|---|---|---|---|
| PFOA | 4.8 ng/L | 4 ng/L | 1.2× |
Also detected, with no federal limit set: lithium (46800 ng/L).
Health-based violations
Separately from PFAS, EPA records 144 health-based violations across 94 of the county’s water systems since 2020, the most recent in 2026. They involved lead and copper, trihalomethanes, total coliform, E. coli, contaminant 0700, gross alpha radiation.
What this means
PFAS are industrial chemicals that EPA describes as breaking down only very slowly in the environment. In April 2024 EPA set the first enforceable national limits: 4 ng/L for PFOA and PFOS, 10 ng/L for PFHxS, PFNA and GenX.
These figures are county-level and come from EPA’s sampling of public water systems. They describe the worst result found in the county, not what comes out of any particular tap — that depends on which system serves the address, and on the plumbing in the building. A private well is not covered by this programme at all.
ZIP codes in Montgomery County
77301 · 77302 · 77303 · 77304 · 77306 · 77316 · 77318 · 77354 · 77355 · 77356 · 77357 · 77362 · 77365 · 77372 · 77378 · 77380 · 77381 · 77382 · 77384 · 77385 · 77386 · 77873
Readings are county-level, so every ZIP here shares the figure above. Search your ZIP on the map to see it in context.