Is Lower Base, MP Tap Water Safe to Drink?
Graded B-, with 20 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
73.4/100
waterverge.com Lower Base, MP — Water Quality Report
Lower Base's drinking water received a grade of B- (73.4 out of 100), indicating fair water quality. The city's 2 water systems serve approximately 3,411 residents using groundwater.
Lead levels were measured at 2.1 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 187 violations on record, including 5 health-based violations. 20 remain unresolved.
What to know about Lower Base's water
Lower Base ranks #2 out of 7 cities in Northern Mariana Islands for water quality, placing it above average in the state.
Lower Base 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 8 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Lower Base, MP water safe to drink?
Lower Base's drinking water has significant quality concerns based on EPA testing data. With a grade of B- (73.4/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 3,411 residents using groundwater (wells).
Recent water quality updates for Lower Base
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Lower Base's water quality assessment. Grade: B- (73.4/100).
Contaminants: Revised Total Coliform Rule.
Contaminants: Lead and Copper Rule, Nitrate.
1 health-based. Contaminants: Groundwater Rule.
Key contaminant findings
Based on the most recent EPA sampling data for Lower Base's water supply.
Well within EPA limits.
Violation history
Lower Base's water system has 187 total violations on record, including 5 health-based violations. 20 remain unresolved. 8 violations were issued in the last 5 years.
Where does Lower Base's water come from?
Lower Base's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 3,411 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate.
What Lower Base residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Lower Base'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. | 2.1 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Lower Base compares by contaminant
Explore where Lower Base ranks among all Northern Mariana Islands cities for specific contaminants.
Water source & infrastructure
Where Lower Base's water comes from
Lower Base'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 private ownership and serves approximately 3,411 people through 2 water systems.
Water systems serving Lower Base
| System Name | PWSID | Population | Source |
|---|---|---|---|
| Saipan Ice And Water | MP0000004 | 3,101 | GW |
| The Water Company | MP0000063 | 310 | GWP |
How Lower Base compares
Full Northern Mariana Islands rankings →Lower Base's score of 73.4/100 is above the average of 56/100 among major Northern Mariana Islands cities. It outscores 5 of 6 nearby cities.
Nearby cities
View Northern Mariana Islands rankings →About Lower Base, 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 Lower Base's water quality findings.
Frequently asked questions
Is Lower Base, MP tap water safe to drink?
Lower Base's water quality earned a grade of B- (73.4/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #2 out of 7 cities tested in Northern Mariana Islands.
What contaminants are in Lower Base's water?
Lead was measured at 2.1 ppb (90th percentile). 187 violations are on record.
How is Lower Base'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 Lower Base?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Lower Base's water come from?
Lower Base's water is sourced from Groundwater. The city has 2 water systems serving approximately 3,411 residents.
What health violations has Lower Base's water system had?
Lower Base has 5 health-based violations on record. The most recent violation was recorded in February 2023. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 20 violations remain unresolved.
Is Lower Base's groundwater at risk of contamination?
Lower Base 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 187 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 Lower Base's water compare to other cities?
Lower Base ranks #2 out of 7 cities in Northern Mariana Islands (better than 71% of state cities) and #10085 out of 15744 cities nationally (36th percentile). The grade of B- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.