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WaterSafeCheck

ZIP Code 91023 Water Quality Report

Mount Wilson, CA · Los Angeles County County

Safety Score
D

Water Safety Grade

Poor — Multiple violations recorded

Health Violations

0

Total Violations

0

Lead Risk

N/A

Contaminants

0

About Tap Water in ZIP Code 91023

Tap water in ZIP code 91023 (Mount Wilson, CA) has received a D grade (score: 53/100) — below average for the nation. SIERRA MADRE-CITY, WATER DEPT. 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

SIERRA MADRE-CITY, WATER DEPT.

EPA ID: CA1910148

Water Source

Surface Water

Population Served

11,000 residents

County

Los Angeles County County, California

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Lead Levels in ZIP 91023

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

Lead Data Not Available

Lead testing data was not found in EPA records for ZIP code 91023. This may occur with very small systems or systems that report under a parent utility. Contact SIERRA MADRE-CITY, WATER DEPT. directly to request lead testing results or a copy of their Consumer Confidence Report.
Lead Exposure Risk Rating
Unknown
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

SIERRA MADRE-CITY, WATER DEPT. has recorded zero violations in the EPA compliance database over the past 5 years — a strong indicator of consistent regulatory compliance and careful monitoring.

Total Violations (5 yr)
0
Health-Based Violations
0
Unresolved Violations
0
Boil Water Advisories
0
Compliance Risk
Unknown
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Contaminants Detected

Contaminants with health-based violations on record

No health-based contaminant violations are on record for ZIP code 91023. 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.

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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
EPA Radon Zone

Moderate potential

Zone 2

EPA Radon Zone 2 — moderate radon potential. The EPA recommends testing your home regardless of zone designation.

🛡 What Should You Do? — ZIP 91023 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 SIERRA MADRE-CITY, WATER DEPT. 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 91023 Water Quality

Is tap water safe to drink in ZIP code 91023?+
Tap water in 91023 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 91023 tap water?+
Lead level data from EPA monitoring is not available for 91023. Contact SIERRA MADRE-CITY, WATER DEPT. directly for the most recent lead testing results.
Who provides tap water to 91023?+
Tap water in ZIP code 91023 is provided by SIERRA MADRE-CITY, WATER DEPT. (EPA ID: CA1910148). This system serves approximately 11,000 residents. You can contact them directly for Consumer Confidence Reports, current advisories, and billing information.
What is the water source for 91023?+
ZIP code 91023 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 91023 have any active water quality violations?+
No active violations are on record for ZIP code 91023. EPA data shows this water system is currently in compliance with Safe Drinking Water Act standards.
How do I get a copy of my water quality report for 91023?+
Your water utility — SIERRA MADRE-CITY, WATER DEPT. — 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 "SIERRA MADRE-CITY, WATER DEPT. Consumer Confidence Report." The EPA's ECHO database also has historical compliance data.
What water filter should I use in 91023?+
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 91023, 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 91023 tap water safe for babies and infants?+
Infants are especially vulnerable to lead, nitrates, and microbial contaminants in drinking water. Current EPA data for 91023 shows no available lead data — we recommend using a certified NSF/ANSI 53 lead filter as a precaution for infant formula. Always consult your pediatrician for guidance specific to your child's health.

Data Sources & Methodology

Water quality data for ZIP code 91023 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 SIERRA MADRE-CITY, WATER DEPT.. 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 →