Is San Jose, MP Tap Water Safe to Drink?
Graded D+, with 46 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
50/100
waterverge.com San Jose, MP — Water Quality Report
San Jose's drinking water received a grade of D+ (50 out of 100), indicating poor water quality. The city's 4 water systems serve approximately 3,495 residents using groundwater.
Lead levels were measured at 1.5 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 433 violations on record, including 13 health-based violations. 46 remain unresolved.
What to know about San Jose's water
San Jose ranks #5 out of 7 cities in Northern Mariana Islands for water quality, placing it below average in the state.
San Jose 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 73 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is San Jose, MP water safe to drink?
San Jose's drinking water has significant quality concerns based on EPA testing data. With a grade of D+ (50/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 4 water systems serve approximately 3,495 residents using groundwater (wells).
Recent water quality updates for San Jose
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into San Jose's water quality assessment. Grade: D+ (50/100).
Contaminants: Nitrate.
3 health-based. Contaminants: Groundwater Rule.
Contaminants: Revised Total Coliform Rule.
Key contaminant findings
Based on the most recent EPA sampling data for San Jose's water supply.
Well within EPA limits.
Violation history
San Jose's water system has 433 total violations on record, including 13 health-based violations. 46 remain unresolved. 73 violations were issued in the last 5 years.
Where does San Jose's water come from?
San Jose's drinking water comes from groundwater (wells), supplied by 4 water systems serving approximately 3,495 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate.
What San Jose residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in San Jose'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.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
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. | 1.5 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how San Jose compares by contaminant
Explore where San Jose ranks among all Northern Mariana Islands cities for specific contaminants.
Water source & infrastructure
Where San Jose's water comes from
San Jose'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 state ownership and serves approximately 3,495 people through 4 water systems.
Water systems serving San Jose
| System Name | PWSID | Population | Source |
|---|---|---|---|
| Commonwealth Utilities Corp (Tinian) | MP0000002 | 3,005 | GW |
| Tinian Ice And Water | MP0000068 | 300 | GWP |
| San Jose Mart Water | MP0000213 | 130 | GWP |
| Modern Stationary | MP0000053 | 60 | GW |
How San Jose compares
Full Northern Mariana Islands rankings →San Jose's score of 50/100 is below the average of 60/100 among major Northern Mariana Islands cities. It outscores 2 of 6 nearby cities. 4 of 6 nearby cities score higher.
Nearby cities
View Northern Mariana Islands rankings →About San Jose, MP
Wikipedia →Saipan is the largest island and capital of the Northern Mariana Islands, an unincorporated territory of the United States in the western Pacific Ocean. According to 2020 estimates by the United States Census Bureau, the population of Saipan was 43,385. Its people have been United States citizens since the 1980s. Saipan is one of the main homes of the Chamorro and the Carolinian, the indigenous people of the Mariana Islands.
Learn more about your water
Guides and resources related to San Jose's water quality findings.
Frequently asked questions
Is San Jose, MP tap water safe to drink?
San Jose's water quality earned a grade of D+ (50/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #5 out of 7 cities tested in Northern Mariana Islands.
What contaminants are in San Jose's water?
Lead was measured at 1.5 ppb (90th percentile). 433 violations are on record.
How is San Jose'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 San Jose?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does San Jose's water come from?
San Jose's water is sourced from Groundwater. The city has 4 water systems serving approximately 3,495 residents.
What health violations has San Jose's water system had?
San Jose has 13 health-based violations on record. The most recent violation was recorded in January 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 46 violations remain unresolved.
Is San Jose's groundwater at risk of contamination?
San Jose 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 433 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 San Jose's water compare to other cities?
San Jose ranks #5 out of 7 cities in Northern Mariana Islands (better than 29% of state cities) and #13083 out of 15744 cities nationally (17th percentile). The grade of D+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.