Water Quality in HOLLISTER, CA (95023)

EPA violation data for public water systems serving ZIP code 95023.

Total Violations

Health-Based

Monitoring / Reporting

Resolved

What does this mean?

81 of 88 violations have been resolved. 5 are health-based violations, meaning contaminant levels exceeded federal safety limits. The remaining 83 are monitoring or reporting violations (missed testing deadlines or late paperwork — not necessarily a water quality issue). Not all violations mean your water is unsafe. The EPA requires reporting even for minor administrative issues.

Water systems: 93 Population served: 67,381

Violations Detail (88 total)

Contaminant	Category	MCL Limit	Measured	Date	Status	Health Effects
E. COLI	Monitoring	0	N/A	Jun 30, 2025	Active	Severe gastrointestinal illness; may be fatal in vulnerable populations
Lead and Copper Rule	Monitoring	N/A	N/A	Jun 30, 2025	Active	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Nov 30, 2024	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Nov 30, 2024	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Nov 30, 2024	Resolved	N/A
LEAD AND COPPER RULE REVISIONS	Monitoring	N/A	N/A	Oct 16, 2024	Active	N/A
LEAD AND COPPER RULE REVISIONS	Health-Based	N/A	N/A	Oct 16, 2024	Active	N/A
LEAD AND COPPER RULE REVISIONS	Monitoring	N/A	N/A	Oct 16, 2024	Active	N/A
LEAD AND COPPER RULE REVISIONS	Health-Based	N/A	N/A	Oct 16, 2024	Active	N/A
E. COLI	Monitoring	0	N/A	Jul 3, 2024	Active	Severe gastrointestinal illness; may be fatal in vulnerable populations
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jun 30, 2024	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jun 30, 2024	Resolved	N/A
Lead and Copper Rule	Monitoring	N/A	N/A	Jun 30, 2024	Resolved	N/A
Public Notice	Monitoring	N/A	N/A	Apr 9, 2024	Resolved	N/A
TTHM	Monitoring	N/A	N/A	Mar 31, 2024	Resolved	N/A
Total Haloacetic Acids (HAA5)	Monitoring	N/A	N/A	Mar 31, 2024	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Mar 31, 2024	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jan 31, 2024	Resolved	N/A
Nitrate	Monitoring	N/A	N/A	Dec 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Revised Total Coliform Rule	Monitoring	N/A	N/A	Dec 31, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Dec 31, 2023	Resolved	N/A
Lead and Copper Rule	Monitoring	N/A	N/A	Dec 31, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jun 30, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jun 30, 2023	Resolved	N/A
Lead and Copper Rule	Monitoring	N/A	N/A	Jun 30, 2023	Resolved	N/A
Consumer Confidence Rule	Monitoring	N/A	N/A	Jun 30, 2023	Resolved	N/A
Nitrate	Monitoring	N/A	N/A	Mar 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Mar 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Dec 31, 2022	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Dec 31, 2022	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Dec 31, 2022	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Dec 31, 2022	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Dec 31, 2022	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Dec 31, 2022	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Dec 31, 2022	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Dec 31, 2022	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Oct 3, 2022	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Lead and Copper Rule	Monitoring	N/A	N/A	Sep 8, 2022	Resolved	N/A
Lead and Copper Rule	Monitoring	N/A	N/A	Sep 8, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jul 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jul 31, 2022	Resolved	N/A
TTHM	Health-Based	N/A	0.086	Jun 30, 2022	Resolved	N/A
TTHM	Health-Based	N/A	0.086	Jun 30, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jun 30, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jun 30, 2022	Resolved	N/A
Lead and Copper Rule	Monitoring	N/A	N/A	Jun 30, 2022	Resolved	N/A
Lead and Copper Rule	Monitoring	N/A	N/A	Jun 30, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2022	Resolved	N/A
CARBON, TOTAL	Health-Based	N/A	N/A	Mar 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Feb 28, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Feb 28, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jan 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jan 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jan 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jan 31, 2022	Resolved	N/A
Nitrate	Monitoring	N/A	N/A	Dec 31, 2021	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Dec 31, 2021	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Revised Total Coliform Rule	Monitoring	N/A	N/A	Dec 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Dec 31, 2021	Resolved	N/A
Lead and Copper Rule	Monitoring	N/A	N/A	Dec 31, 2021	Resolved	N/A
Lead and Copper Rule	Monitoring	N/A	N/A	Dec 31, 2021	Resolved	N/A
Total Haloacetic Acids (HAA5)	Monitoring	N/A	N/A	Sep 30, 2021	Resolved	N/A
TTHM	Monitoring	N/A	N/A	Sep 30, 2021	Resolved	N/A
Total Haloacetic Acids (HAA5)	Monitoring	N/A	N/A	Sep 30, 2021	Resolved	N/A
TTHM	Monitoring	N/A	N/A	Sep 30, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jul 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jul 31, 2021	Resolved	N/A
Consumer Confidence Rule	Monitoring	N/A	N/A	Jun 30, 2021	Resolved	N/A
Consumer Confidence Rule	Monitoring	N/A	N/A	Jun 30, 2021	Resolved	N/A
Lead and Copper Rule	Monitoring	N/A	N/A	Jun 30, 2021	Resolved	N/A
Lead and Copper Rule	Monitoring	N/A	N/A	Jun 30, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Apr 30, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Mar 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Feb 28, 2021	Resolved	N/A

Lead & Copper Levels

Violation Timeline

2025(2)

E. COLI

Jun 30Active

Lead and Copper Rule

Jun 30Active

2024(16)

Revised Total Coliform Rule

Nov 30Resolved

Revised Total Coliform Rule

Nov 30Resolved

Revised Total Coliform Rule

Nov 30Resolved

LEAD AND COPPER RULE REVISIONS

Oct 16Active

LEAD AND COPPER RULE REVISIONS

Oct 16Active

LEAD AND COPPER RULE REVISIONS

Oct 16Active

LEAD AND COPPER RULE REVISIONS

Oct 16Active

E. COLI

Jul 3Active

Revised Total Coliform Rule

Jun 30Resolved

Revised Total Coliform Rule

Jun 30Resolved

Lead and Copper Rule

Jun 30Resolved

Public Notice

Apr 9Resolved

TTHM

Mar 31Resolved

Total Haloacetic Acids (HAA5)

Mar 31Resolved

Revised Total Coliform Rule

Mar 31Resolved

Revised Total Coliform Rule

Jan 31Resolved

How Does This Compare?

HOLLISTER (95023) has 88 recorded violations, including 5 health-based. 7 remain unresolved. Consider testing your tap water independently for added peace of mind.

Recommended Water Filters

Based on the contaminants detected in your area, these filter types may help improve your water quality.

Reverse Osmosis System

Highly effective at removing heavy metals, dissolved solids, and a wide range of contaminants. Recommended for homes with lead or arsenic concerns.

Targets:Lead, Copper, Arsenic, Mercury, Cadmium

Look for:NSF/ANSI 58 certified

NSF Certified Products → EPA Safe Drinking Water Guide →

Activated Carbon Filter

Excellent for removing chlorine, chloramine, and disinfection byproducts like THMs and HAAs. Available as pitcher filters, countertop, or under-sink units.

Targets:THMs, HAAs, Chlorine, Chloramine, Taste & Odor

Look for:NSF/ANSI 42 & 53 certified

NSF Certified Products → EPA Safe Drinking Water Guide →

UV Water Purifier

Uses ultraviolet light to neutralize bacteria, viruses, and parasites without chemicals. Ideal for homes with microbial contamination concerns.

Targets:E. coli, Coliform, Giardia, Cryptosporidium

Look for:NSF/ANSI 55 (Class A) certified

NSF Certified Products → EPA Safe Drinking Water Guide →

Always look for filters certified by NSF International for the specific contaminants you want to remove.

Water Quality in HOLLISTER, CA (95023)

What does this mean?

Violations Detail (88 total)

Lead & Copper Levels

Violation Timeline

2025(2)

2024(16)

2023(10)

2022(40)

2021(20)

How Does This Compare?

Recommended Water Filters

Reverse Osmosis System

Activated Carbon Filter

UV Water Purifier

Nearby ZIP Codes

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