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Community Water System · PWS AZ0410001

Ajo Improvement Company

Ajo, Arizona 85321 - drinking water served from groundwater sources to 2,654 people, tracked in EPA SDWIS and UCMR5.

2,654
People served
85
EPA violations
0
Health-based
Untested
UCMR5 result

The verdict

EPA records 85 drinking-water violations at Ajo Improvement Company - below the Arizona per-system average.

85
Total EPA violations on record
0%
Health-based (MCL / treatment failure)
2,654
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Ajo Improvement Company

Ajo Improvement Company is a public/private-owned community water system that delivers drinking water to 2,654 residents in Ajo, Arizona (Pima County) through 1,200 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 85 total violations for this system , of which 0 (0%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 71 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 Chlorine, recorded in 20 violations (MR). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across Arizona, EPA tracks 1,493 public water systems serving 7,322,166 people, with 228,944 cumulative violations and 15,663 health-based violations on record. About 98% of systems in the state carry at least one violation, and state-wide the average per system is 153.3 violations. Statewide, 145 of 152 UCMR5-tested systems have reported PFAS detections (95.4%).

Ajo Improvement Company's 85 violations sit below the Arizona 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
2,654
Total Violations
85
Health-Based Violations
0
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Public/Private
Connections
1,200
County
Pima
School/Daycare
No
MCL Violations
0
Monitoring Violations
71
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Chlorine MR 20 2020
Total Haloacetic Acids (HAA5) MR 13 2024
TTHM MR 13 2024
Arsenic MR 7 2023
Revised Total Coliform Rule RPT 6 2024
Nitrate MR 4 2004
Consumer Confidence Rule Other 4 2015
Coliform (TCR) MR 4 2005
Revised Total Coliform Rule MON 2 2016
Cadmium MR 1 1988
Fluoride MR 1 1988
Gross Alpha, Excl. Radon and U MR 1 1988
Barium MR 1 1988
Selenium MR 1 1988
Mercury MR 1 1988
Lead and Copper Rule MR 1 2005
Chromium MR 1 1988

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 Ajo Improvement Company.

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 AZ0410001 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Arizona Drinking Water Authority

Arizona DEQ, Drinking Water Program is the primacy agency that licenses and inspects Ajo Improvement Company under EPA-delegated authority.

Open AZ regulator portal

Source: Arizona DEQ, Drinking Water Program

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 Total Haloacetic Acids (HAA5) MR 13 SDWIS / AZ0410001 / 2456
2024 TTHM MR 13 SDWIS / AZ0410001 / 2950
2024 Revised Total Coliform Rule RPT 6 SDWIS / AZ0410001 / 8000
2023 Arsenic MR 7 SDWIS / AZ0410001 / 1005
2020 Chlorine MR 20 SDWIS / AZ0410001 / 0999
2016 Revised Total Coliform Rule MON 2 SDWIS / AZ0410001 / 8000
2015 Consumer Confidence Rule Other 4 SDWIS / AZ0410001 / 7000
2005 Coliform (TCR) MR 4 SDWIS / AZ0410001 / 3100
2005 Lead and Copper Rule MR 1 SDWIS / AZ0410001 / 5000
2004 Nitrate MR 4 SDWIS / AZ0410001 / 1040
1988 Cadmium MR 1 SDWIS / AZ0410001 / 1015
1988 Fluoride MR 1 SDWIS / AZ0410001 / 1025
1988 Gross Alpha, Excl. Radon and U MR 1 SDWIS / AZ0410001 / 4000
1988 Barium MR 1 SDWIS / AZ0410001 / 1010
1988 Selenium MR 1 SDWIS / AZ0410001 / 1045

How Ajo Improvement Company Compares

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

Metric Ajo Improvement Company Arizona avg Federal benchmark
Total violations 85 153.3 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 0 10.5 Indicates a contaminant exceeded a federal MCL
PFAS detection None 95.4% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 2,654 4,904 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 1,493 regulated public water systems in Arizona.

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 Ajo Improvement Company water safe to drink? ▼
Ajo Improvement Company (PWS ID: AZ0410001) has 85 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 2,654 people using Groundwater sources.
How many people does Ajo Improvement Company serve? ▼
Ajo Improvement Company serves 2,654 people in Ajo, Arizona. It is a Public/Private-owned system using Groundwater water sources with 1,200 service connections.
What type of violations does Ajo Improvement Company have? ▼
Ajo Improvement Company has 85 total violations: 0 health-based violations (MCL exceedances or treatment failures), 71 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Ajo Improvement Company water? ▼
No PFAS testing data is available for Ajo Improvement Company under the EPA's UCMR5 monitoring program.
What water source does Ajo Improvement Company use? ▼
Ajo Improvement Company uses Groundwater 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.