Is Chico, CA 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 ↓
42.4/100
waterverge.com Chico, CA — Water Quality Report
Chico's drinking water received a grade of F (42.4 out of 100), indicating failing water quality. The city's 30 water systems serve approximately 23,374 residents using purchased surface water.
Lead levels were measured at 1.4 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 644 violations on record, including 306 health-based violations. 63 remain unresolved.
What to know about Chico's water
Chico ranks #665 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.
Hexavalent chromium (chromium-6) was detected at 0.90 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 67 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Chico, CA water safe to drink?
Chico's drinking water has significant quality concerns based on EPA testing data. With a grade of F (42.4/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 30 water systems serve approximately 23,374 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Chico
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Chico's water quality assessment. Grade: F (42.4/100).
Contaminants: Lead and Copper Rule.
Contaminants: Consumer Confidence Rule.
1 health-based. Contaminants: Surface Water Treatment Rule.
Federal disaster declaration (FEMA DR-3592). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-4683). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Chico'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
Chico's water system has 644 total violations on record, including 306 health-based violations. 63 remain unresolved. 67 violations were issued in the last 5 years.
Flood & environmental risk
Butte County has experienced 8 federally declared disasters since 1964. 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 Butte C Nr Chico.
Where does Chico's water come from?
Chico's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 30 water systems serving approximately 23,374 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Butte C Nr Chico (river).
What Chico residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Chico'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.
Chico'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 ↓Violation summary
Violations & advisories
Flood & disaster history
Butte County has experienced 8 federally declared disasters since 1964. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Chico'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. | 1.4 | 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 |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Chico compares by contaminant
Explore where Chico ranks among all California cities for specific contaminants.
Water source & infrastructure
Where Chico's water comes from
Chico'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 private ownership and serves approximately 23,374 people through 30 water systems.
Water bodies near Chico
Chico 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 Chico
| System Name | PWSID | Population | Source |
|---|---|---|---|
| DEL ORO WATER CO.-PARADISE PINES | CA0410011 | 10,940 | SWP |
| DEL ORO WATER CO-FERNDALE | CA1210007 | 1,662 | GW |
| DEL ORO WATER COMPANY - STRAWBERRY DIV. | CA5510007 | 1,295 | SW |
| DEL ORO RIVER ISLAND SERV TERR #1 | CA5400665 | 1,280 | SW |
| DEL ORO CALIFORNIA PINES DISTRICT | CA5410034 | 944 | GW |
| DEL ORO WATER CO.-JOHNSON PARK | CA4510015 | 904 | GW |
| DEL ORO WATER CO.-LIME SADDLE MARINA | CA0405001 | 895 | SW |
| DEL ORO TRAVER DISTRICT | CA5400553 | 657 | GW |
| DEL ORO WATER CO.-STIRLING BLUFFS | CA0410018 | 521 | SW |
| GRIDLEY FARM LABOR HOUSING | CA0400012 | 460 | GW |
| BUTTE CREEK ESTATES MUTUAL WATER CO | CA0400007 | 399 | GW |
| BENBOW-DEL ORO W.C. | CA1200671 | 370 | SW |
| DEL ORO WATER CO.-MAGALIA | CA0410009 | 340 | GW |
| DEL ORO GRANDVIEW GARDENS DISTRICT | CA5400666 | 323 | GW |
| DEL ORO WC - COUNTRY ESTATES DIST | CA1500314 | 297 | GW |
| GRAN MUTUAL WATER CO | CA0400008 | 290 | GW |
| DEL ORO WC - BLACK BUTTE DISTRICT | CA1100404 | 277 | GW |
| ALMOND GROVE MOBILE PARK | CA0400040 | 253 | GW |
| DEL ORO WC - ARBUCKLE DISTRICT | CA0605011 | 185 | GW |
| DEL ORO WATER CO. - HAT CREEK DISTRICT | CA4500022 | 185 | SW |
| KEEFER CREEK ESTATES | CA0400151 | 160 | GW |
| SIERRA MOON MUTUAL WATER COMPANY | CA0409183 | 120 | GW |
| DEL ORO WC - LARKSPUR MEADOWS | CA5200574 | 116 | GW |
| DEL ORO WATER COMPANY - BUZZTAIL DIST. | CA0400091 | 106 | GW |
| DEL ORO WATER CO - METROPOLITAN DISTRICT | CA1000057 | 92 | GW |
| DEL ORO RIVER ISLAND SERV TERR #2 | CA5402048 | 89 | GW |
| BLUE OAK TERRACE MUTUAL | CA0409181 | 81 | GW |
| FOREST KNOLLS MUTUAL WATER CO | CA0400078 | 46 | GW |
| DEL ORO EAST PLANO DISTRICT | CA5400767 | 46 | GW |
| HARTLEY MUTUAL WATER SYSTEM | CA0400003 | 41 | GW |
How Chico compares
Full California rankings →Chico's score of 42.4/100 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 Chico, CA
Wikipedia →Chico is the most populous city in Butte County, California, United States. Located in the Sacramento Valley region of Northern California, the city had a population of 101,475 in the 2020 census, an increase from 86,187 in the 2010 census. Chico is the cultural and economic center of the northern Sacramento Valley, as well as the most populous city in California north of the capital city of Sacramento. The city is known as a college town, as the home of California State University, Chico, and for Bidwell Park, one of the largest urban parks in the world.
Learn more about your water
Guides and resources related to Chico's water quality findings.
Explore water quality across Butte
Frequently asked questions
Is Chico, CA tap water safe to drink?
Chico's water quality earned a grade of F (42.4/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #665 out of 694 cities tested in California.
What contaminants are in Chico's water?
Lead was measured at 1.4 ppb (90th percentile). 644 violations are on record.
How is Chico'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 Chico?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Chico's water come from?
Chico's water is sourced from Purchased surface water. The city has 30 water systems serving approximately 23,374 residents.
What health violations has Chico's water system had?
Chico has 306 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. 63 violations remain unresolved.
How does Chico's water compare to other cities?
Chico ranks #665 out of 694 cities in California (better than 4% of state cities) and #14810 out of 15744 cities nationally (6th percentile). The grade of F reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.