Community Water System · PWS NN4903072

Mexican Water NTUA

Ft Defiance, Navajo Nation 86504 - drinking water served from surface water sources to 294 people, tracked in EPA SDWIS and UCMR5.

Compiled by PlainWater Editorial, Drinking Water Quality Editorial Team · May 15, 2026

294
People served: 141
EPA violations: 36
Health-based: Untested
UCMR5 result

The verdict

EPA records 141 drinking-water violations at Mexican Water NTUA, 26% of them health-based - below the Navajo Nation per-system average.

141
Total EPA violations on record: 26%
Health-based (MCL / treatment failure): 294
People served by this system: N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Mexican Water NTUA

Mexican Water NTUA is a native american-owned community water system that delivers drinking water to 294 residents in Ft Defiance, Navajo Nation through 86 service connections. Its water is drawn from surface water sources. EPA's Safe Drinking Water Information System records 141 total violations for this system , of which 36 (26%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 62 monitoring and reporting violations are on file. The most recent violation on record dates to 2024.

The most frequently cited contaminant at this system is Arsenic, recorded in 36 violations (MCL, health-based). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across Navajo Nation, EPA tracks 170 public water systems serving 167,275 people, with 29,535 cumulative violations and 1,366 health-based violations on record. About 100% of systems in the state carry at least one violation, and state-wide the average per system is 173.7 violations. Statewide, 13 of 13 UCMR5-tested systems have reported PFAS detections (100%).

Mexican Water NTUA's 141 violations sit below the Navajo Nation average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

Population Served

294

Total Violations

141

Health-Based Violations

Water Source

Surface Water

System Details

System Type: Community
Owner Type: Native American
Connections: 86
School/Daycare: No
MCL Violations: 36
Monitoring Violations: 62
Treatment Tech Violations: 0

Violation History

Contaminant violations recorded by EPA.

Contaminant	Category	Count	Latest
Arsenic	MCL	36	2024
Public Notice	Other	15	2024
Arsenic	MR	5	2022
Coliform (TCR)	MR	3	2012
Stage 2 Disinfectants and Disinfection Byproducts Rule	MR	3	2013
CYANIDE	MR	3	2008
1,2-DIBROMO-3-CHLOROPROPANE	MR	2	2011
ETHYLENE DIBROMIDE	MR	2	2011
Xylenes, Total	MR	2	2011
Vinyl chloride	MR	2	2011
1,2-Dichloroethane	MR	2	2011
Carbon tetrachloride	MR	2	2011
1,1,2-Trichloroethane	MR	2	2011
CHLOROBENZENE	MR	2	2011
Benzene	MR	2	2011
Styrene	MR	2	2011
Revised Total Coliform Rule	Other	2	2016
cis-1,2-Dichloroethylene	MR	2	2011
Trichloroethylene	MR	2	2011
1,1-Dichloroethylene	MR	2	2011
DICHLOROMETHANE	MR	2	2011
Ethylbenzene	MR	2	2011
1,1,1-Trichloroethane	MR	2	2011
p-Dichlorobenzene	MR	2	2011
1,2,4-Trichlorobenzene	MR	2	2011
1,2-Dichloropropane	MR	2	2011
Toluene	MR	2	2011
trans-1,2-Dichloroethylene	MR	2	2011
Tetrachloroethylene	MR	2	2011
o-Dichlorobenzene	MR	2	2011

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Mexican Water NTUA.

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID NN4903072 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Navajo Nation Drinking Water Authority

Navajo Nation's primacy agency administers the Safe Drinking Water Act locally. Search EPA SDWIS for the current state contact, or use the state's public health or environment department portal.

Find NN regulator via EPA SDWIS

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest)	Contaminant	Category	Count	EPA Record
2024	Arsenic	MCL	36	SDWIS / NN4903072 / 1005
2024	Public Notice	Other	15	SDWIS / NN4903072 / 7500
2022	Arsenic	MR	5	SDWIS / NN4903072 / 1005
2021	Revised Total Coliform Rule	MON	1	SDWIS / NN4903072 / 8000
2016	Revised Total Coliform Rule	Other	2	SDWIS / NN4903072 / 8000
2013	Stage 2 Disinfectants and Disinfection Byproducts Rule	MR	3	SDWIS / NN4903072 / 0600
2012	Coliform (TCR)	MR	3	SDWIS / NN4903072 / 3100
2011	1,2-DIBROMO-3-CHLOROPROPANE	MR	2	SDWIS / NN4903072 / 2931
2011	ETHYLENE DIBROMIDE	MR	2	SDWIS / NN4903072 / 2946
2011	Xylenes, Total	MR	2	SDWIS / NN4903072 / 2955
2011	Vinyl chloride	MR	2	SDWIS / NN4903072 / 2976
2011	1,2-Dichloroethane	MR	2	SDWIS / NN4903072 / 2980
2011	Carbon tetrachloride	MR	2	SDWIS / NN4903072 / 2982
2011	1,1,2-Trichloroethane	MR	2	SDWIS / NN4903072 / 2985
2011	CHLOROBENZENE	MR	2	SDWIS / NN4903072 / 2989

How Mexican Water NTUA Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric	Mexican Water NTUA	Navajo Nation avg	Federal benchmark
Total violations	141	173.7	SDWA compliance, any non-zero count is a recorded breach
Health-based violations	36	8	Indicates a contaminant exceeded a federal MCL
PFAS detection	None	100%	EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served	294	984	Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 170 regulated public water systems in Navajo Nation.

Federal MCL reference, Safe Drinking Water Act thresholds ▼

Contaminant	Federal MCL / Action Level	Note
Lead	0 mg/L (Action Level: 0.015 mg/L)	Lead and Copper Rule treatment technique
Arsenic	0.010 mg/L (10 ppb)	Health-based MCL since 2006
Total Coliform	Treatment technique (RTCR)	Indicator organism, monitoring trigger
PFOA / PFOS (PFAS)	4.0 ppt each (final 2024 rule)	Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N)	10 mg/L	Acute health risk for infants

Frequently Asked Questions

Is Mexican Water NTUA water safe to drink? ▼

Mexican Water NTUA (PWS ID: NN4903072) has 141 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 294 people using Surface Water sources.

How many people does Mexican Water NTUA serve? ▼

Mexican Water NTUA serves 294 people in Ft Defiance, Navajo Nation. It is a Native American-owned system using Surface Water water sources with 86 service connections.

What type of violations does Mexican Water NTUA have? ▼

Mexican Water NTUA has 141 total violations: 36 health-based violations (MCL exceedances or treatment failures), 62 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.

Has PFAS been detected in Mexican Water NTUA water? ▼

No PFAS testing data is available for Mexican Water NTUA under the EPA's UCMR5 monitoring program.

What water source does Mexican Water NTUA use? ▼

Mexican Water NTUA uses Surface Water as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.

Where does this data come from? ▼

All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.

Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. This data is provided for informational purposes only.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.