Is Ajo, AZ Tap Water Safe to Drink?
Graded B-, with 25 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
70.6/100
waterverge.com Ajo, AZ — Water Quality Report
Ajo's drinking water received a grade of B- (70.6 out of 100), indicating fair water quality. The city's 3 water systems serve approximately 5,159 residents using groundwater.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 163 violations on record, including 0 health-based violations. 25 remain unresolved.
What to know about Ajo's water
Ajo ranks #148 out of 292 cities in Arizona for water quality, placing it below average in the state.
Ajo relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
The system has seen 13 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Ajo, AZ water safe to drink?
Ajo's drinking water has significant quality concerns based on EPA testing data. With a grade of B- (70.6/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 3 water systems serve approximately 5,159 residents using groundwater (wells).
Recent water quality updates for Ajo
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Ajo's water quality assessment. Grade: B- (70.6/100).
Contaminants: Revised Total Coliform Rule.
Contaminants: Revised Total Coliform Rule.
Contaminants: Revised Total Coliform Rule.
Federal disaster declaration (FEMA DR-3241). Hurricane event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-977). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Ajo's water supply.
Well within EPA limits.
Violation history
Ajo's water system has 163 total violations on record, including 0 health-based violations. 25 remain unresolved. 13 violations were issued in the last 5 years.
Flood & environmental risk
Pima County has experienced 9 federally declared disasters since 1966. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies.
Where does Ajo's water come from?
Ajo's drinking water comes from groundwater (wells), supplied by 3 water systems serving approximately 5,159 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate.
What Ajo residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Ajo's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Ajo's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Drought conditions
D2 — severe droughtPima County is currently in D2 (severe drought) per the U.S. Drought Monitor (week of May 5, 2026). Drought can elevate disinfection-byproduct (TTHM/HAA5) levels and taste/odor issues as utilities draw from lower reservoirs.
Source: U.S. Drought Monitor, updated weekly by NDMC, USDA, and NOAA.
Flood & disaster history
Pima County has experienced 9 federally declared disasters since 1966. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Ajo compares by contaminant
Explore where Ajo ranks among all Arizona cities for specific contaminants.
Water source & infrastructure
Where Ajo's water comes from
Ajo's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by public/private ownership and serves approximately 5,159 people through 3 water systems.
Water systems serving Ajo
| System Name | PWSID | Population | Source |
|---|---|---|---|
| AJO IMPROVEMENT COMPANY | AZ0410001 | 2,654 | GW |
| ARIZONA WATER CO - AJO | AZ0410003 | 2,100 | GWP |
| AJO DWID | AZ0410153 | 405 | GWP |
How Ajo compares
Full Arizona rankings →Ajo's score of 70.6/100 is above the average of 42/100 among major Arizona cities. It outscores 10 of 10 nearby cities.
Nearby cities
View Arizona rankings →Learn more about your water
Guides and resources related to Ajo's water quality findings.
Explore water quality across Pima
Frequently asked questions
Is Ajo, AZ tap water safe to drink?
Ajo's water quality earned a grade of B- (70.6/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #148 out of 292 cities tested in Arizona.
What contaminants are in Ajo's water?
Lead was measured at 0.0 ppb (90th percentile). 163 violations are on record.
How is Ajo's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Ajo?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Ajo's water come from?
Ajo's water is sourced from Groundwater. The city has 3 water systems serving approximately 5,159 residents.
Is Ajo's groundwater at risk of contamination?
Ajo uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 163 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Ajo's water compare to other cities?
Ajo ranks #148 out of 292 cities in Arizona (better than 49% of state cities) and #10703 out of 15744 cities nationally (32th percentile). The grade of B- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.