Is Arroyo Grande, CA Tap Water Safe to Drink?
Graded F — but Chlorate was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
40.5/100
waterverge.com Arroyo Grande, CA — Water Quality Report
Arroyo Grande's drinking water received a grade of F (40.5 out of 100), indicating failing water quality. The city's 13 water systems serve approximately 23,710 residents using purchased surface water.
Lead levels were measured at 0.0 ppb (90th percentile), well within EPA limits. UCMR 5 testing detected 7 PFAS compounds, with levels exceeding EPA maximum contaminant levels in the water supply.
The system has 158 violations on record, including 93 health-based violations. 19 remain unresolved.
What to know about Arroyo Grande's water
Arroyo Grande ranks #676 out of 694 cities in California for water quality, placing it among the lowest-rated 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.
Of particular concern: PFAS "forever chemical" levels exceed the 2024 EPA maximum contaminant levels. These synthetic compounds don't break down naturally and require specialized filtration such as reverse osmosis or granular activated carbon.
Hexavalent chromium (chromium-6) was detected at 1.41 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 39 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Arroyo Grande, CA water safe to drink?
Arroyo Grande's drinking water has significant quality concerns based on EPA testing data. With a grade of F (40.5/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 13 water systems serve approximately 23,710 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Arroyo Grande
A timeline of significant water quality events, violations, and data updates.
PFAS levels exceed EPA maximum contaminant levels. Reverse osmosis or activated carbon filtration recommended.
Latest EPA compliance and testing data incorporated into Arroyo Grande's water quality assessment. Grade: F (40.5/100).
2 health-based. Contaminants: Nitrate, Selenium.
2 health-based. Contaminants: Nitrate, Selenium.
Contaminants: Revised Total Coliform Rule.
Federal disaster declaration (FEMA DR-3592). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Arroyo Grande's water supply.
Well within EPA limits.
PFAS "forever chemicals" exceed EPA maximum contaminant levels. Reverse osmosis or granular activated carbon filtration strongly recommended.
PFAS "forever chemicals" detected
UCMR 5 testing found 7 PFAS compounds in Arroyo Grande's water supply. PFAS are synthetic chemicals that persist indefinitely in the environment and the human body.
Violation history
Arroyo Grande's water system has 158 total violations on record, including 93 health-based violations. 19 remain unresolved. 39 violations were issued in the last 5 years.
Flood & environmental risk
San Luis Obispo County has experienced 10 federally declared disasters since 1973. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Lopez C Nr Arroyo Grande.
Where does Arroyo Grande's water come from?
Arroyo Grande's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 13 water systems serving approximately 23,710 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Lopez C Nr Arroyo Grande (river).
What Arroyo Grande residents can do
Recommended: Reverse osmosis system. This addresses the specific contaminants found in Arroyo Grande'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.
Arroyo Grande'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 ↓Forever chemicals overview
National PFAS report →Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Arroyo Grande
Industrial polluters nearby
Reported releases to surface water by facilities near Arroyo Grande, ranked by pounds discharged annually.
Total reported releases to surface water: 71 lbs
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
PHILLIPS 66 CO-SANTA MARIA REFINERY ARROYO GRANDE, CA93420 | Phenol | 71 | 5.3 mi |
PROMEGA CORP SAN LUIS OBISPO, CA93401 | — | — | 9.9 mi |
CALPORTLAND CO SAN LUIS OBISPO SAN LUIS OBISPO, CA93401 | — | — | 9.7 mi |
ENTEGRIS - SAN LUIS OBISPO SAN LUIS OBISPO, CA93401 | — | — | 9.0 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Flood & disaster history
San Luis Obispo County has experienced 10 federally declared disasters since 1973. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Arroyo Grande'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. | 0.0 | 15 | ppb | Inorganic | Safe |
| 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. | 60.000 | HI | µg/L | PFAS | 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. | 0.011 | HI | µg/L | PFAS | 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. | 0.004 | HI | µg/L | PFAS | 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. | 0.005 | HI | µg/L | PFAS | 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. | 0.006 | 0.004 | µg/L | PFAS | Over MCL |
| 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. | 0.007 | 0.004 | µg/L | PFAS | Over MCL |
| 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. | 0.004 | HI | µg/L | PFAS | 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)
See how Arroyo Grande compares by contaminant
Explore where Arroyo Grande ranks among all California cities for specific contaminants.
Water source & infrastructure
Where Arroyo Grande's water comes from
Arroyo Grande'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 23,710 people through 13 water systems.
Water bodies near Arroyo Grande
Arroyo Grande is located near 1 notable water body. As a surface water system, these water bodies may directly influence the city's drinking water supply.
Water systems serving Arroyo Grande
| System Name | PWSID | Population | Source |
|---|---|---|---|
| CITY OF ARROYO GRANDE UTILITIES DIVISION | CA4010001 | 17,963 | SWP |
| WOODLANDS DEVELOPMENT | CA4010081 | 3,862 | GW |
| MESA DUNES MOBILE HOME ESTATES | CA4000650 | 600 | GW |
| WOODLAND PARK MUTUAL WATER CO | CA4000506 | 538 | GW |
| CANYON CREST MUTUAL BENEFIT WC | CA4000230 | 133 | SWP |
| EDNA VALLEY RANCH EAST | CA4000202 | 132 | GW |
| VARIAN RANCH MUTUAL WATER | CA4000765 | 106 | GW |
| KEN MAR GARDENS | CA4000648 | 84 | GW |
| LAGUNA NEGRA MUTUAL WATER CO. | CA4000705 | 80 | GW |
| H2O, INC | CA4000741 | 70 | GW |
| COUNTRY HILLS ESTATES | CA4000637 | 60 | GW |
| RANCHO NIPOMO WATER COMPANY | CA4000771 | 44 | GW |
| TERRA DE ORO WATER COMPANY | CA4000749 | 38 | GW |
How Arroyo Grande compares
Full California rankings →Arroyo Grande's score of 40.5/100 is below the average of 57/100 among major California cities. It outscores 4 of 10 nearby cities. 6 of 10 nearby cities score higher.
Nearby cities
View California rankings →About Arroyo Grande, CA
Learn more about your water
Guides and resources related to Arroyo Grande's water quality findings.
Explore water quality across San Luis Obispo
Frequently asked questions
Is Arroyo Grande, CA tap water safe to drink?
Arroyo Grande's water quality earned a grade of F (40.5/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #676 out of 694 cities tested in California.
What contaminants are in Arroyo Grande's water?
Lead was measured at 0.0 ppb (90th percentile). 7 PFAS compounds were detected. 158 violations are on record.
How is Arroyo Grande'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 Arroyo Grande?
PFAS compounds exceed EPA limits — a reverse osmosis or activated carbon filter is recommended.
Where does Arroyo Grande's water come from?
Arroyo Grande's water is sourced from Purchased surface water. The city has 13 water systems serving approximately 23,710 residents.
What health violations has Arroyo Grande's water system had?
Arroyo Grande has 93 health-based violations on record. The most recent violation was recorded in October 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 19 violations remain unresolved.
Why does Arroyo Grande have so many PFAS compounds in its water?
7 different PFAS "forever chemical" compounds were detected in Arroyo Grande's water supply during UCMR 5 testing. PFAS contamination often originates from proximity to military installations (AFFF firefighting foam), airports, industrial manufacturing sites, or wastewater treatment facilities. Some levels exceed the 2024 EPA maximum contaminant levels — a reverse osmosis or NSF-certified activated carbon filter is strongly recommended.
How does Arroyo Grande's water compare to other cities?
Arroyo Grande ranks #676 out of 694 cities in California (better than 3% of state cities) and #15133 out of 15744 cities nationally (4th percentile). The grade of F reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.