Is Las Piedras, PR Tap Water Safe to Drink?
Graded F — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
43.8/100
waterverge.com Las Piedras, PR — Water Quality Report
Las Piedras's drinking water received a grade of F (43.8 out of 100), indicating failing water quality. The city's 5 water systems serve approximately 83,376 residents using surface water.
Lead levels were measured at 3.0 ppb (90th percentile), well within EPA limits. PFAS testing under UCMR 5 found no detectable forever chemicals.
The system has 1090 violations on record, including 374 health-based violations. 65 remain unresolved.
What to know about Las Piedras's water
Las Piedras ranks #67 out of 101 cities in Puerto Rico for water quality, placing it below average in the state.
The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection.
Haloacetic acid (HAA5) levels were elevated at 34.1 µg/L in UCMR 4 testing, though below the 60 µg/L EPA limit. Activated carbon filtration can help reduce these disinfection byproducts.
Hexavalent chromium (chromium-6) was detected at 0.06 µg/L in UCMR 3 testing. While below California's 10 µg/L limit and with no federal MCL set, residents sensitive to this contaminant may consider reverse osmosis filtration.
The system has seen 89 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Las Piedras, PR water safe to drink?
Las Piedras's drinking water has significant quality concerns based on EPA testing data. With a grade of F (43.8/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 5 water systems serve approximately 83,376 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Las Piedras
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Las Piedras's water quality assessment. Grade: F (43.8/100).
Contaminants: Revised Total Coliform Rule.
Contaminants: Revised Total Coliform Rule.
Contaminants: Revised Total Coliform Rule.
Key contaminant findings
Based on the most recent EPA sampling data for Las Piedras's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Las Piedras's water system has 1,090 total violations on record, including 374 health-based violations. 65 remain unresolved. 89 violations were issued in the last 5 years.
Where does Las Piedras's water come from?
Las Piedras's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 5 water systems serving approximately 83,376 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Rio Espiritu Santo Nr Rio Grande (river), Rio Grande Nr El Verde (river), Rio Mameyes Nr Sabana (river), Rio Sabana (river), Rio Fajardo (river).
What Las Piedras residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Las Piedras'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 ↓Forever chemicals overview
National PFAS report →Violation summary
Violations & advisories
Recommended water filters
Based on contaminants detected in Las Piedras's water supply, we recommend the following filter types.
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. | 3.0 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 1.85 | 1.3 | mg/L | Inorganic | Over Limit |
| 11Cl-PF3OUdS | ND | HI | µg/L | PFAS | Not Detected |
| 4:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 6:2 FTS 6:2 FTSPFAS A fluorotelomer sulfonate commonly found at sites contaminated with aqueous film-forming foam (AFFF) used in firefighting. Health EffectsPotential liver toxicity and endocrine disruption. Less studied but identified as a contaminant of concern. EPA LimitNo individual MCL (not yet regulated) Common SourcesFirefighting foam (AFFF), airports, military bases, and industrial facilities. | ND | HI | µg/L | PFAS | Not Detected |
| 8:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 9Cl-PF3ONS | ND | HI | µg/L | PFAS | Not Detected |
| ADONA | ND | HI | µg/L | PFAS | Not Detected |
| HFPO-DA HFPO-DA (GenX)PFAS A replacement for PFOA in manufacturing, marketed as safer but still a persistent "forever chemical." Also known as GenX. Health EffectsLiver and kidney effects, reproductive toxicity, immune system effects, and potential cancer risk. EPA Limit10 ppt MCL Common SourcesFluoropolymer manufacturing (used as PFOA replacement), industrial wastewater discharge. | ND | 0.01 | µg/L | PFAS | Not Detected |
| lithium LithiumInorganic A naturally occurring alkali metal found in groundwater. Monitored under UCMR 5 to assess occurrence in drinking water. Health EffectsKidney effects at high doses. Low-level exposure effects under study; some research suggests neurological effects. EPA LimitNo MCL (monitoring only under UCMR 5) Common SourcesNatural mineral deposits, geothermal water, and industrial discharge. | ND | HI | µg/L | PFAS | Not Detected |
| NEtFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| NFDHA | ND | HI | µg/L | PFAS | Not Detected |
| NMeFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| PFBA PFBAPFAS One of the shortest-chain PFAS compounds. Very mobile in water and difficult to remove with standard filtration. Health EffectsThyroid effects, potential developmental toxicity. Shorter half-life in body than long-chain PFAS. EPA LimitNo individual MCL (not yet regulated) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and firefighting foam. | ND | HI | µg/L | PFAS | Not Detected |
| PFBS PFBSPFAS A short-chain PFAS used as a replacement for PFOS. While it clears the body faster than long-chain PFAS, it still persists in the environment. Health EffectsThyroid effects, reproductive and developmental toxicity, kidney effects. EPA LimitPart of Hazard Index (1.0) Common SourcesIndustrial discharge, firefighting foam, and as a replacement chemical in manufacturing. | ND | HI | µg/L | PFAS | Not Detected |
| PFDA | ND | HI | µg/L | PFAS | Not Detected |
| PFDoA | ND | HI | µg/L | PFAS | Not Detected |
| PFEESA | ND | HI | µg/L | PFAS | Not Detected |
| PFHpA PFHpAPFAS A medium-chain PFAS compound found in various environmental samples. Less studied than PFOA/PFOS but still considered a contaminant of concern. Health EffectsLiver effects, potential developmental toxicity, and endocrine disruption. EPA LimitPart of Hazard Index (1.0) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFHpS | ND | HI | µg/L | PFAS | Not Detected |
| PFHxA PFHxAPFAS A short-chain PFAS replacement chemical widely used after manufacturers phased out longer-chain PFAS. Very commonly detected in water. Health EffectsLiver and kidney effects, potential thyroid disruption. Considered less toxic than long-chain PFAS but still persistent. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial processes, firefighting foam (AFFF), food packaging, and textile treatment. | ND | HI | µg/L | PFAS | Not Detected |
| PFHxS PFHxSPFAS A medium-chain PFAS found in firefighting foam and consumer products. It has a long half-life in the human body, similar to long-chain PFAS. Health EffectsImmune system effects, thyroid disruption, and potential reproductive and developmental harm. EPA LimitPart of Hazard Index (1.0) Common SourcesFirefighting foam (AFFF), waterproof textiles, food packaging, and industrial discharge. | ND | HI | µg/L | PFAS | Not Detected |
| PFMBA | ND | HI | µg/L | PFAS | Not Detected |
| PFMPA | ND | HI | µg/L | PFAS | Not Detected |
| PFNA PFNAPFAS A long-chain PFAS compound used in manufacturing fluoropolymers. It bioaccumulates in the body and is very persistent in the environment. Health EffectsDevelopmental effects, liver toxicity, immune suppression, and potential cancer risk. EPA LimitPart of Hazard Index (1.0) Common SourcesFluoropolymer manufacturing, industrial emissions, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFOA PFOAPFAS A long-chain PFAS ("forever chemical") once widely used in nonstick coatings and firefighting foam. It persists in the body and environment for years. Health EffectsLinked to kidney and testicular cancer, thyroid disease, elevated cholesterol, and reproductive issues. EPA Limit4.0 ppt MCL Common SourcesIndustrial discharge, firefighting foam (AFFF), nonstick cookware manufacturing, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFOS PFOSPFAS A long-chain PFAS compound historically used in stain-resistant coatings and firefighting foam. One of the most studied and persistent PFAS chemicals. Health EffectsLiver damage, immune system suppression, thyroid disruption, increased cholesterol, and potential cancer risk. EPA Limit4.0 ppt MCL Common SourcesFirefighting foam (AFFF), industrial sites, stain-resistant fabric treatments, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFPeA PFPeAPFAS A short-chain PFAS compound commonly detected in drinking water. One of the most frequently found PFAS in UCMR 5 monitoring. Health EffectsLess studied than PFOA/PFOS. Potential liver and thyroid effects. Research is ongoing. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial discharge, firefighting foam degradation, and consumer products. | ND | HI | µg/L | PFAS | Not Detected |
| PFPeS | ND | HI | µg/L | PFAS | Not Detected |
| PFTA | ND | HI | µg/L | PFAS | Not Detected |
| PFTrDA | ND | HI | µg/L | PFAS | Not Detected |
| PFUnA | ND | HI | µg/L | PFAS | Not Detected |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Las Piedras compares by contaminant
Explore where Las Piedras ranks among all Puerto Rico cities for specific contaminants.
Water source & infrastructure
Where Las Piedras's water comes from
Las Piedras's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards.
These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge.
The system is operated by local government ownership and serves approximately 83,376 people through 5 water systems.
Water bodies near Las Piedras
Las Piedras is located near 5 notable water bodies. As a surface water system, these water bodies may directly influence the city's drinking water supply.
Water systems serving Las Piedras
| System Name | PWSID | Population | Source |
|---|---|---|---|
| RIO BLANCO,VIEQUES,CULEDRA | PR0005386 | 80,759 | SW |
| COM. RANCHO GRANDE | PR0653026 | 1,428 | SW |
| CUBUY MAIZALES | PR0005286 | 617 | SW |
| ACUED. LOMAS DEL VIENTO-MAIZALES | PR0653066 | 400 | SW |
| ACUED. DE LA COM. DEL DUQUE | PR0653056 | 172 | SW |
How Las Piedras compares
Full Puerto Rico rankings →Las Piedras's score of 43.8/100 is above the average of 38/100 among major Puerto Rico cities. It outscores 10 of 10 nearby cities.
Nearby cities
View Puerto Rico rankings →About Las Piedras, PR
Wikipedia →Naguabo is a town and municipality in Puerto Rico located in the east coast of the island bordered by the Vieques Passage, north of Humacao; south of Río Grande and Ceiba; and east of Las Piedras. Naguabo is spread over eight barrios and Naguabo Pueblo. The municipality is composed of the barrios of Daguao, Río, Mariana, Peña Pobre, Pueblo, Río Blanco, Maizales, Santiago y Lima, and Duque. It is part of the San Juan-Caguas-Guaynabo Metropolitan Statistical Area.
Learn more about your water
Guides and resources related to Las Piedras's water quality findings.
Explore water quality across Las Piedras Municipio
Frequently asked questions
Is Las Piedras, PR tap water safe to drink?
Las Piedras's water quality earned a grade of F (43.8/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #67 out of 101 cities tested in Puerto Rico.
What contaminants are in Las Piedras's water?
Lead was measured at 3.0 ppb (90th percentile). No PFAS compounds were detected. 1090 violations are on record.
How is Las Piedras'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 Las Piedras?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Las Piedras's water come from?
Las Piedras's water is sourced from Surface water. The city has 5 water systems serving approximately 83,376 residents.
What health violations has Las Piedras's water system had?
Las Piedras has 374 health-based violations on record. The most recent violation was recorded in December 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 65 violations remain unresolved.
How does Las Piedras's water compare to other cities?
Las Piedras ranks #67 out of 101 cities in Puerto Rico (better than 34% of state cities) and #14513 out of 15744 cities nationally (8th percentile). The grade of F reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.