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CHICO, California Tap Water Quality

23,049 people served · 28 water systems

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Failing

CHICO, California is a small city with 23,049 residents served by 28 distinct public water systems. Water service covers ZIP codes 95926, 95927, 95928, 95973.

CHICO has accumulated a significant number of EPA health-based violations. Reviewing the contaminants involved, requesting your utility's Consumer Confidence Report, and using certified point-of-use filtration is strongly advisable.

EPA reporting identifies Nitrate, Coliform Bacteria, Uranium, and Lead among the regulated contaminants associated with CHICO's recent health-based violations. Each contaminant has different sources, health implications, and recommended mitigation steps — links to the full EPA reference for each are listed alongside the violation history below.

Last updated: 2026-05-18 · Source: EPA SDWIS

Location

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Centered on ZIP-code centroids of water systems serving this city.

ZIP Codes Served

Health-Based Violations (Last 5 Years)

EPA Maximum Contaminant Level exceedances reported by water systems serving CHICO. Each entry explains the contaminant, the health risk, and recommended precautions, and links to a full guide.

EPA Code 0200 · Treatment Technique Violation

2

violations

EPA Limit

0 per 100 mL presence/absence

Last Reading

First Reported

Feb 2025

Most Recent

Feb 2025

What this violation means

Total coliform bacteria are themselves usually harmless, but their presence signals that the water distribution system has a vulnerability — typically a cracked pipe, loss of pressure, or back-siphonage — that could allow disease-causing pathogens to enter. Repeated coliform-positive samples trigger mandatory utility investigation.

Recommended precautions

  • If your utility issues a boil-water advisory, boil all drinking and cooking water for at least one minute.
  • Use bottled water until the advisory is lifted.
  • Ice from icemakers and beverages made before the advisory should be discarded.
  • UV light and chlorination both kill coliform bacteria — most home filters do not.
Leadchemical

EPA Code 5200 · Treatment Technique Violation

4

violations

EPA Limit

0.015 mg/L

Last Reading

First Reported

Oct 2024

Most Recent

Oct 2024

What this violation means

Lead is a potent neurotoxin with no safe exposure level. In drinking water it primarily enters via corroded lead service lines, lead-soldered copper pipes, and brass fixtures. Children under 6 and pregnant women face the highest risk because lead disrupts developing nervous and skeletal systems.

Recommended precautions

  • Run cold tap water 30–120 seconds before drinking or cooking, especially after the tap has been unused for hours.
  • Never cook with hot tap water — heat increases lead leaching from pipes.
  • Use an NSF/ANSI 53 certified filter for lead removal (carbon block or reverse osmosis).
  • If you have children, get blood lead levels tested by your pediatrician.
Nitratechemical

EPA Code 1040 · Maximum Contaminant Level Exceedance

13

violations

EPA Limit

10 mg/L

Last Reading

11 MG/L

First Reported

Jan 2021

Most Recent

Aug 2024

What this violation means

Nitrate contamination is most acute in agricultural regions where fertilizer and animal waste leach into groundwater. The immediate risk is to formula-fed infants under 6 months — high nitrate levels prevent their blood from carrying oxygen, causing 'blue baby syndrome.' Pregnant women should also avoid high-nitrate water.

Recommended precautions

  • Never give untreated high-nitrate water to infants — use bottled water for formula.
  • Boiling does NOT remove nitrate. Boiling concentrates it.
  • Reverse osmosis, ion exchange, or distillation are the only effective home treatments.
  • Private well owners in farming areas should test annually for nitrate.
Uraniumradiological

EPA Code 4006 · Maximum Contaminant Level Exceedance

14

violations

EPA Limit

0.03 mg/L

Last Reading

41.3 PCI/L

First Reported

Jan 2021

Most Recent

Apr 2024

What this violation means

Uranium in drinking water is both a chemical toxin (kidney damage) and a radiological hazard (increased cancer risk). It's most commonly found in groundwater near uranium ore deposits or former mining activity in the Western US.

Recommended precautions

  • Reverse osmosis is the gold standard for removing uranium.
  • Ion exchange systems work but must be sized correctly for uranium.
  • If you live near former mining sites, test for uranium even if not required.

Source: EPA Safe Drinking Water Information System (SDWIS). Health-based violations only. Older violations may have been resolved; check your utility's most recent Consumer Confidence Report for current status.

Water Systems Serving CHICO

KEEFER CREEK ESTATES

PWSID: CA0400151

160 served

DEL ORO WATER CO.-JOHNSON PARK

PWSID: CA4510015

904 served

DEL ORO WATER CO-FERNDALE

PWSID: CA1210007

1,662 served

BENBOW-DEL ORO W.C.

PWSID: CA1200671

370 served

DEL ORO WC - BLACK BUTTE DISTRICT

PWSID: CA1100404

277 served

DEL ORO WATER CO.-LIME SADDLE MARINA

PWSID: CA0405001

895 served

DEL ORO WATER CO.-MAGALIA

PWSID: CA0410009

340 served

DEL ORO WATER CO.-PARADISE PINES

PWSID: CA0410011

10,940 served

DEL ORO WATER CO.-STIRLING BLUFFS

PWSID: CA0410018

521 served

DEL ORO WC - ARBUCKLE DISTRICT

PWSID: CA0605011

185 served

DEL ORO WATER CO - METROPOLITAN DISTRICT

PWSID: CA1000057

92 served

4 violations

DEL ORO WC - COUNTRY ESTATES DIST

PWSID: CA1500314

297 served

DEL ORO WATER COMPANY - STRAWBERRY DIV.

PWSID: CA5510007

1,295 served

2 violations

DEL ORO WC - LARKSPUR MEADOWS

PWSID: CA5200574

116 served

DEL ORO WATER CO. - HAT CREEK DISTRICT

PWSID: CA4500022

185 served

DEL ORO WATER COMPANY - BUZZTAIL DIST.

PWSID: CA0400091

106 served

DEL ORO TRAVER DISTRICT

PWSID: CA5400553

657 served

4 violations

DEL ORO RIVER ISLAND SERV TERR #1

PWSID: CA5400665

1,280 served

19 violations

DEL ORO RIVER ISLAND SERV TERR #2

PWSID: CA5402048

89 served

DEL ORO CALIFORNIA PINES DISTRICT

PWSID: CA5410034

944 served

HARTLEY MUTUAL WATER SYSTEM

PWSID: CA0400003

41 served

1 violation

GRIDLEY FARM LABOR HOUSING

PWSID: CA0400012

460 served

BUTTE CREEK ESTATES MUTUAL WATER CO

PWSID: CA0400007

399 served

GRAN MUTUAL WATER CO

PWSID: CA0400008

290 served

BLUE OAK TERRACE MUTUAL

PWSID: CA0409181

81 served

SIERRA MOON MUTUAL WATER COMPANY

PWSID: CA0409183

120 served

1 violation

ALMOND GROVE MOBILE PARK

PWSID: CA0400040

253 served

1 violation

WEST COTTONWOOD APARTMENTS

PWSID: CA4500247

90 served

1 violation

What Can You Do?

  • ✅ Request your utility's annual Consumer Confidence Report (CCR) — required by law.
  • ✅ Use an NSF-certified water filter if violations involve lead, arsenic, or PFAS.
  • ✅ Run cold water for 30 seconds before drinking if you have older plumbing (reduces lead).
  • ✅ Check back monthly — we update data from the EPA every 30 days.

About this data

This overview reflects EPA SDWIS data published as of 2026-05-18. It covers active Community Water Systems (CWS) that exceeded federal Maximum Contaminant Levels during the past five-year EPA reporting window. For up-to-the-minute information, request a current Consumer Confidence Report from your utility, or review the EPA's public dashboard.

Frequently Asked Questions

Is CHICO, California tap water safe to drink?

This city's water had numerous EPA violations in the last 5 years. Consider filtered water.

How many EPA violations does CHICO have?

CHICO has 33 EPA health-based water violations in the last 5 years across 28 water systems serving 23,049 people.

What contaminants have been found in CHICO water?

The following EPA-regulated contaminants have been detected: 1040, 0200, 4006, 5200. View details about each contaminant, health effects, and recommended precautions above in the violations table.

Should I use a water filter in CHICO?

Using an NSF-certified water filter is recommended if your area has violations involving lead, arsenic, or PFAS. For other contaminants, consult your local water utility. Check the annual Consumer Confidence Report (CCR) for detailed guidance.

What should I do if there are violations in CHICO?

Request your water utility's annual Consumer Confidence Report (CCR), which is required by the EPA. Follow the utility's guidance on boil water advisories. Run cold water for 30 seconds before drinking if you have older plumbing. Use an NSF-certified filter if needed based on your water system's violations.

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