Fort Defiance-Window Rock-St Michaels Ntua
Fort Defiance-Window Rock-St Michaels Ntua (EPA ID NN0403000) in Ft Defiance, AZ supplies groundwater (wells) to about 12,869 people: 7 violations since 2016, latest lead result 1.6 ppb, PFAS not detected.
Health-based violations since 2016: TTHM, Revised Total Coliform Rule. All are listed as resolved.
90th-percentile lead in the latest round (Jan 2023). Lead comes mostly from household plumbing and service lines, so individual homes can be higher.
None of the tested PFAS were found above EPA’s reporting limits in 2023–2025.
System facts
Health-based violations
| Contaminant or rule | Health-based violations since 2016 |
|---|---|
| TTHM | 6 |
| Revised Total Coliform Rule | 1 |
A health-based violation means a contaminant exceeded its legal limit (MCL) or a required treatment technique was not met, as reported by the state to EPA’s SDWIS. All are listed as resolved or archived; the latest began Feb 2025.
Lead
90th-percentile lead per sampling round (90% of the homes sampled were at or below this level). Black line: EPA’s 15 ppb action level; under the Lead and Copper Rule Improvements the action level becomes 10 ppb from 2027.
PFAS
| Compound | Highest result | Samples with detection | EPA limit |
|---|---|---|---|
| PFHxA | not detected | 0 of 14 | — |
| PFPeA | not detected | 0 of 14 | — |
| PFBA | not detected | 0 of 14 | — |
| HFPO-DA (GenX) | not detected | 0 of 14 | — |
| PFHpA | not detected | 0 of 14 | — |
| PFDA | not detected | 0 of 14 | — |
| PFOA | not detected | 0 of 14 | 4 ppt MCL |
| PFOS | not detected | 0 of 14 | 4 ppt MCL |
| PFNA | not detected | 0 of 14 | — |
| PFHxS | not detected | 0 of 14 | — |
| PFBS | not detected | 0 of 14 | — |
EPA Fifth Unregulated Contaminant Monitoring Rule (UCMR 5), samples 2023–2025; ppt = parts per trillion (ng/L). The 4.0 ppt maximum contaminant levels for PFOA and PFOS were set by EPA in 2024; water systems have until the end of the decade to comply.
What this is — and isn’t. These are records your water utility and state reported to the EPA, and the EPA’s radon map for your county. They describe the system and the area, not the water from your own tap or the air in your home. For that, read your utility’s annual Consumer Confidence Report and test: lead and radon tests are inexpensive.
Questions
Has Fort Defiance-Window Rock-St Michaels Ntua had drinking water violations?
Health-based violations since 2016: TTHM, Revised Total Coliform Rule. All are listed as resolved.
What is the lead level in Fort Defiance-Window Rock-St Michaels Ntua water?
The latest 90th-percentile lead result (Jan 2023) was 1.6 ppb. EPA’s action level is 15 ppb (10 ppb from 2027).
Does Fort Defiance-Window Rock-St Michaels Ntua have PFAS in its water?
None of the tested PFAS were found above EPA’s reporting limits in 2023–2025.