01The verdict: is As Matuis water safe?
As Matuis's drinking water has significant quality concerns based on EPA testing data. With a grade of C+ (68.4/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 634 residents using groundwater (wells).
Lead is over its legal limit
Measured at 19.0 ppb against the EPA Action Level of 15 ppb. The ledger below shows how far over — and which filter removes it.
See the measurement ↓Top half in Northern Mariana Islands
As Matuis ranks #3 of 7 graded Northern Mariana Islands cities.
See the comparison ↓3 violations in the last five years
Recent compliance history is the best predictor of future problems — the year-by-year record is below.
See the record ↓As Matuis's drinking water received a grade of C+ (68.4 out of 100), indicating fair water quality. The city's 1 water system serves approximately 634 residents using groundwater.
Lead levels were measured at 19.0 ppb (90th percentile), which exceeds the EPA action level of 15 ppb. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 71 violations on record, including 0 health-based violations. 16 remain unresolved.
As Matuis ranks #3 out of 7 cities in Northern Mariana Islands for water quality, placing it mid-range in the state. As Matuis 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. Lead levels exceed the EPA action level of 15 ppb, which typically indicates aging lead service lines or lead solder in the distribution system. An NSF 53-certified filter is strongly recommended for drinking and cooking water. As a small community water system, As Matuis may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in As Matuis's water
Every contaminant flagged in As Matuis, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Over Limit — EPA Action Level: 15 ppb
Exceeds the EPA action level. Lead enters at the service line, not the treatment plant — your address matters more than the city average. Lead service line replacement and an NSF 53-certified point-of-use filter are recommended.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. | 19.0 | 15 | ppb | Inorganic | Over Limit |
03As Matuis's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 71 violations on record, including 0 health-based violations. 16 remain unresolved.
7 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▼ Down 41 ppb since 2016. The latest reading (19 ppb, 2025) is over the action level. Sampled at higher-risk homes (90th percentile).
04Where As Matuis's water comes from
As Matuis's drinking water is drawn from underground aquifers through wells.
Groundwater
Underground aquifers reached by wells — naturally filtered, but can carry minerals like arsenic and nitrate.
Local treatment
Groundwater generally needs less treatment — typically disinfection and, where needed, mineral removal.
1 system
1 water system, operated under private ownership.
634 people
Residents served across As Matuis's service area.
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 634 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| Kensington Hotel | MP0000071 | 634 | Groundwater |
05How As Matuis compares
Scores for nearby Northern Mariana Islands cities on one line, with the average marked.
dashed line = Northern Mariana Islands average (57/100)
As Matuis scores 68.4/100 — above the Northern Mariana Islands average of 57/100. It outscores 4 of 6 nearby cities.
40.2 / 100BLower Base, MP
73.4 / 100DSan Jose, MP
50 / 100BSinapalu, MP
78.2 / 100DChalan Lau Lau, MP
48.3 / 100DSan Antonio, MP
50.9 / 100
06What to do at home
Steps matched to what testing actually found in As Matuis's water — not generic advice.
Filter drinking & cooking water
NSF 53-certified pitcher or under-sink filter. Lead level (19.0 ppb) exceeds the EPA action level of 15 ppb
Compare tested filters →Flush taps & check your service line
Lead leaches from pipes as water sits. Run cold water 30 seconds before drinking (especially mornings), and ask the utility whether your address still has a lead service line.
Lead risks explained →Watch for As Matuis alerts
We refresh EPA data monthly and surface new violations, advisories, and boil-water notices for your county on this page.
All water alerts →Frequently asked questions
Is As Matuis, MP tap water safe to drink?
As Matuis's water quality earned a grade of C+ (68.4/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #3 out of 7 cities tested in Northern Mariana Islands.
What contaminants are in As Matuis's water?
Lead was measured at 19.0 ppb (90th percentile). 71 violations are on record.
How is As Matuis'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 As Matuis?
Yes — lead levels exceed the EPA action level of 15 ppb. We recommend an NSF 53-certified filter or reverse osmosis system. Based on current data, basic filtration should suffice for additional peace of mind.
Where does As Matuis's water come from?
As Matuis's water is sourced from Groundwater. The city has 1 water system serving approximately 634 residents.
Is As Matuis's groundwater at risk of contamination?
As Matuis 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 71 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 As Matuis's water compare to other cities?
As Matuis ranks #3 out of 7 cities in Northern Mariana Islands (better than 57% of state cities) and #10921 out of 15382 cities nationally (29th percentile). The grade of C+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does As Matuis's small water system affect quality?
As Matuis's system serves approximately 634 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 71 violations on record.