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WaterSafeCheck

ZIP Code 94558 Water Quality Report

Napa, CA · Napa County County

Safety Score
D

Water Safety Grade

Poor — Multiple violations recorded

Health Violations

0

Total Violations

1

Lead Risk

Very High

Contaminants

0

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Active Water Quality Issues Detected

EPA records show 1 unresolved violation. Contact City of Napa, for current status.

About Tap Water in ZIP Code 94558

Tap water in ZIP code 94558 (Napa, CA) has received a D grade (score: 53/100) — below average for the nation. City of Napa, has recorded notable violations with EPA Safe Drinking Water Act regulations. Residents may want to consider additional filtration and review their annual Consumer Confidence Report.

Water System

City of Napa,

EPA ID: CA2810003

Water Source

Surface Water

Population Served

84,804 residents

County

Napa County County, California

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Lead Levels in ZIP 94558

EPA action level: 15 ppb | Public health goal: 0 ppb

Lead Level: 102.5 ppb — EXCEEDS EPA Action Level

The 90th percentile lead level in 94558 is 102.5 ppb, which EXCEEDS the EPA action level of 15 ppb. This is a serious concern. The water utility is legally required to notify residents, identify the source of contamination, and take corrective action. Do not give this water to infants, children, or pregnant women without first passing it through a certified NSF/ANSI 53 water filter. Contact City of Napa, immediately for current guidance, or call the EPA Safe Drinking Water Hotline at 1-800-426-4791.

Lead exposure risk in 94558 is rated Very High. EPA models estimate a 79% probability of lead exposure risk in this ZIP code based on housing age, infrastructure age, and water system data. This is among the highest risk categories nationally, often associated with heavily aging infrastructure and pre-1986 construction. Do not give unfiltered tap water to children under 6 or pregnant women. Consider getting your home's plumbing tested for lead solder and fixtures.

Lead Level (90th percentile)
102.50 ppb (0.1025 mg/L)
Copper Level (90th percentile)

EPA action level: 1.3 mg/L

1.6 mg/L
Lead Exposure Risk Rating
Very High
Lead Exposure Probability

EPA model estimate based on housing age and infrastructure

79%
Note: Lead levels above are the 90th percentile from EPA monitoring — meaning 90% of samples were at or below this level. Even "undetected" tap water lead doesn't account for lead leaching from home plumbing. If your home was built before 1986, individual tap testing is recommended.
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Violation History

Past 5 years — EPA SDWIS data

City of Napa, has recorded 1 violation, but none are health-based. Administrative or reporting violations don't directly indicate unsafe water, but they do signal gaps in documentation or monitoring procedures. 1 violation is currently unresolved — meaning the issue has not yet been formally corrected in EPA records. This is a serious concern that residents should follow up on with their water utility.

Total Violations (5 yr)
1
Health-Based Violations
0
Unresolved Violations
1
Boil Water Advisories
0
Compliance Risk
Moderate

Regulatory compliance risk is rated Moderate. City of Napa, has had occasional lapses in compliance but generally meets Safe Drinking Water Act requirements.

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Contaminants Detected

Contaminants with health-based violations on record

No health-based contaminant violations are on record for ZIP code 94558. This means EPA monitoring has not found levels of regulated contaminants exceeding the Maximum Contaminant Levels (MCLs) set under the Safe Drinking Water Act — a positive indicator of water quality compliance.

⚖ Enforcement Actions

10 enforcement actions have been issued against City of Napa, — a high number that reflects sustained compliance struggles. Enforcement actions escalate from administrative orders to financial penalties when utilities repeatedly fail to meet safe drinking water standards.
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Water Source & Environmental Factors

Surface Water

This system draws water from lakes, rivers, or reservoirs. Surface water is treated to remove sediment, microorganisms, and chemical contaminants before reaching taps.

Water Source Type
Surface Water
CCR Source Classification
Surface Water
EPA Radon Zone

Lower potential

Zone 3
Annual Flood Risk Cost

Estimated annual flood-related costs per property

$10
Energy Burden

% of household income spent on energy — indicator of older infrastructure

3.33%

EPA Radon Zone 3 — lower radon potential, though the EPA still recommends testing all homes.

🛡 What Should You Do? — ZIP 94558 Recommendations

  • 🚨 Install a certified NSF/ANSI 53 or 58 (reverse osmosis) filter immediately for drinking and cooking
  • 🚨 Do not give unfiltered water to children, pregnant women, or immunocompromised individuals
  • 🚨 Contact City of Napa, to request the current violation status and corrective action plan
  • 🚨 Report concerns to your state environmental agency or call the EPA hotline: 1-800-426-4791
  • 🚨 Consider having your home's tap water independently tested by a certified lab

Frequently Asked Questions — ZIP 94558 Water Quality

Is tap water safe to drink in ZIP code 94558?+
Tap water in 94558 has a below-average water quality grade of D. While it is treated, there have been notable compliance issues. We strongly recommend using a certified NSF/ANSI 53 water filter for drinking and cooking, especially for vulnerable populations.
What is the lead level in 94558 tap water?+
The 90th percentile lead level in 94558 is 102.5 ppb (parts per billion). The EPA action level is 15 ppb. This exceeds the EPA action level — use a certified lead-reducing water filter.
Who provides tap water to 94558?+
Tap water in ZIP code 94558 is provided by City of Napa, (EPA ID: CA2810003). This system serves approximately 84,804 residents. You can contact them directly for Consumer Confidence Reports, current advisories, and billing information.
What is the water source for 94558?+
ZIP code 94558 is served by surface water. Surface water systems draw from rivers, lakes, or reservoirs and must meet strict EPA treatment requirements including filtration and disinfection.
Does 94558 have any active water quality violations?+
Yes — there are currently 1 unresolved violation on record for this water system. Unresolved violations indicate issues that have not yet been formally corrected in EPA tracking systems. Contact City of Napa, for the latest update.
How do I get a copy of my water quality report for 94558?+
Your water utility — City of Napa, — is required by law to send you an annual Consumer Confidence Report (CCR) by July 1 each year. You can also request it directly from the utility or find it online by searching "City of Napa, Consumer Confidence Report." The EPA's ECHO database also has historical compliance data.
What water filter should I use in 94558?+
The right filter depends on what contaminants are present. For lead, look for a filter certified to NSF/ANSI Standard 53. For chlorine byproducts (like THMs), NSF/ANSI 42 filters work well. For a broad range of contaminants including PFAS, look for NSF/ANSI 58 (reverse osmosis) systems. For ZIP code 94558, with a clean compliance record, a standard carbon block filter meeting NSF/ANSI 42 is a good choice for taste and as a precaution.
Is 94558 tap water safe for babies and infants?+
Infants are especially vulnerable to lead, nitrates, and microbial contaminants in drinking water. Given the detected lead level of 102.5 ppb in 94558, we recommend using a certified NSF/ANSI 53 water filter or certified bottled water for preparing infant formula. Always consult your pediatrician for guidance specific to your child's health.

Data Sources & Methodology

Water quality data for ZIP code 94558 is compiled from the EPA Safe Drinking Water Information System (SDWIS), EPA ECHO enforcement database, UCMR5 unregulated contaminant monitoring, and Consumer Confidence Reports filed by City of Napa,. Safety scores are composite metrics derived from violation history, lead levels, enforcement actions, and infrastructure risk indicators. Data reflects a 5-year monitoring window. Last dataset update: 2024. View EPA source data →