Community Water System · PWS NN0400283
Inscription House-Navajo Mountain NTUA
Operator location Ft Defiance, Navajo Nation - upper-third violation load (> 74 violations) with 175 EPA violations; groundwater source; 1,368 served (PWS-level, not municipal population).
- 1,368
- People served (this PWS)
- 175
- EPA violations (this PWS)
- 2
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
Inscription House-Navajo Mountain NTUA standing, high SDWIS violation third
175 EPA SDWIS violations on record - upper-third violation load (> 74 violations). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 1% is middle-third health share (≤ 23%). Population rank #16,777 of 29,740 among systems serving 500+.
The verdict
Inscription House-Navajo Mountain NTUA sits in the upper third of the sitemap cohort by violation count (175), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is mid-pack at 1,368 (mid served population (≤ 3,309)). Health-based share is 1% (middle-third health share (≤ 23%)). No UCMR5 PFAS test appears for this system in this extract.
- #16,777 of 29,740
- Population · /systems
- #27 of 82
- Population · NN
- 175
- Total EPA violations on record
- 1%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Community
- Owner Type
- Native American
- Connections
- 400
- School/Daycare
- No
- MCL Violations
- 2
- Monitoring Violations
- 8
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MR | 5 | 2012 |
| Coliform (TCR) | MCL | 2 | 2013 |
| Stage 2 Disinfectants and Disinfection Byproducts Rule | MR | 1 | 2013 |
| Revised Total Coliform Rule | Other | 1 | 2016 |
| Nitrate | MR | 1 | 2005 |
| Nitrite | MR | 1 | 2010 |
Violation Count vs. the National Corpus
Inscription House-Navajo Mountain NTUA has 175 recorded EPA violations, 83% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 17% carry more. 1% of this system's own violations are health-based (2 of 175), and it ranks #16,777 of 29,740 by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
175 Higher than most more violations than 83% of 29,740 water systems
the national water-system corpus, bucketed by value
Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS · 2026-05-15
SDWIS compliance record for Inscription House-Navajo Mountain NTUA
175 violations on record for NN0400283; use EPA SDWIS to confirm return-to-compliance dates and monitoring categories.
Sources: EPA SDWIS
Nationwide peers
175 violations · 1,368 served: nearest cross-state SDWIS matches.
Cross-state systems with comparable violation load
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
Cross-state systems near this population served
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Inscription House-Navajo Mountain NTUA
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Navajo Nation compares on the same EPA violation measures. Navajo Nation systems
- Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
- Find and compare another public water system by name or PWSID. Search systems
EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.