Community Water System · PWS NN3503059
Sanostee-Tocito NTUA
Operator location Ft Defiance, Navajo Nation - 0% of 99 violations are health-based (lower-third health share (≤ 1%)); groundwater source; 1,953 served per SDWIS.
- 1,953
- People served (this PWS) Middle third of systems
- 99
- EPA violations (this PWS) Upper third of systems
- 0
- Health-based (this PWS) Lower third by health-based share
- Untested
- UCMR5 (this PWS) No UCMR5 result
Sanostee-Tocito NTUA standing, high SDWIS violation third
0% of 99 recorded violations are health-based - lower-third health share (≤ 1%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 0% is lower-third health share (≤ 1%). Population rank #13,837 of 29,740 among systems serving 500+.
The verdict
Sanostee-Tocito NTUA sits in the upper third of the sitemap cohort by violation count (99), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is mid-pack at 1,953 (mid served population (≤ 3,309)). Health-based share is only 0% - almost all of this trail is monitoring or reporting. No UCMR5 PFAS test appears for this system in this extract.
- #13,837 of 29,740
- Population · /systems
- #15 of 82
- Population · NN
- 99
- Total EPA violations on record
- 0%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
Based on EPA SDWIS violation history and UCMR5 PFAS testing only, not water taste, odor, infrastructure age, or contaminants outside the federally tracked set.
System Details
- System Type
- Community
- Owner Type
- Native American
- Connections
- 571
- School/Daycare
- No
- MCL Violations
- 0
- Monitoring Violations
- 91
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MR | 13 | 2012 |
| Fluoride | MR | 5 | 2011 |
| Stage 2 Disinfectants and Disinfection Byproducts Rule | MR | 3 | 2013 |
| Total Haloacetic Acids (HAA5) | MR | 3 | 2020 |
| TTHM | MR | 3 | 2020 |
| Arsenic | MR | 1 | 2008 |
| Barium | MR | 1 | 2008 |
| Chromium | MR | 1 | 2008 |
| Selenium | MR | 1 | 2008 |
| Thallium, Total | MR | 1 | 2008 |
| Endrin | MR | 1 | 2008 |
| BHC-GAMMA | MR | 1 | 2008 |
| Methoxychlor | MR | 1 | 2008 |
| Diquat | MR | 1 | 2008 |
| Glyphosate | MR | 1 | 2008 |
| Picloram | MR | 1 | 2008 |
| Dinoseb | MR | 1 | 2008 |
| Carbofuran | MR | 1 | 2008 |
| LASSO | MR | 1 | 2008 |
| 2,3,7,8-TCDD | MR | 1 | 2008 |
| Heptachlor | MR | 1 | 2008 |
| 2,4,5-TP | MR | 1 | 2008 |
| Benzo(a)pyrene | MR | 1 | 2008 |
| Pentachlorophenol | MR | 1 | 2008 |
| 1,2,4-Trichlorobenzene | MR | 1 | 2008 |
| cis-1,2-Dichloroethylene | MR | 1 | 2008 |
| 1,2-DIBROMO-3-CHLOROPROPANE | MR | 1 | 2008 |
| ETHYLENE DIBROMIDE | MR | 1 | 2008 |
| Chlordane | MR | 1 | 2008 |
| Vinyl chloride | MR | 1 | 2008 |
Violation Count vs. the National Corpus
Sanostee-Tocito NTUA has 99 recorded EPA violations, 73% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 27% carry more. 0% of this system's own violations are health-based (0 of 99), and it ranks #13,837 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)
99 Around the middle fewer violations than 27% 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
How many violations vs. how serious, among peer systems
Sanostee-Tocito NTUA plotted against 29 peer public water systems (500+ people served), by total violation count (x) and the share of those violations that are health-based (y). The crosshair sits at this sample's own median on each axis. A high violation count does not automatically mean a serious record: most monitoring and reporting violations are minor, not health-based.
Violation volume vs. health-based share
Health-based violations on Sanostee-Tocito NTUA
0 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for NN3503059.
Sources: EPA SDWIS
Nationwide peers
99 violations · 1,953 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 Sanostee-Tocito 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.
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.