Water Quality in Glendora, CA: 2 Violations — Grade B
Grade B · Score 83/100 · 1 water system · Updated 2026-05-03
Glendora's water is mostly safe. Minor violations exist but are primarily monitoring-related.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
Glendora in CA has 2 EPA water violations documented — the compliance history below covers what was flagged and which local systems are associated with each finding.
Water Quality by ZIP Code in Glendora
Water quality varies across Glendora's 2 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 91740 | B | 83 | 1 | 0 | View report → |
| 91741 | B | 83 | 1 | 0 | View report → |
Water Quality Overview
Glendora, California receives a water quality grade of B with an overall score of 83 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 1 water system serving Glendora have accumulated 2 EPA violations (all monitoring/reporting type). These violations are tracked across 2 ZIP codes serving approximately 49,934 people.
What Grade B Means
A grade of B indicates good compliance with EPA drinking water standards. While not perfect, Glendora's water systems meet the vast majority of federal requirements. Minor violations may exist but typically relate to monitoring or reporting rather than health-based standards.
Lead Levels
The average 90th percentile lead level across Glendora water systems is 0.0035 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 85% of homes built before 1986, Glendora has a higher-than-average risk of lead from older plumbing. Lead solder was banned in 1986, and homes built before this date may have lead in pipes, solder joints, or fixtures.
Radon Risk
Glendora is in EPA Radon Zone 2 (Moderate risk). Testing is recommended, especially for homes with basements or ground-level living spaces.
Water Systems Serving Glendora
Glendora is served by 1 community water system regulated under the Safe Drinking Water Act. These systems collectively serve approximately 49,934 people across 2 ZIP codes.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 4 enforcement actions against water systems serving Glendora. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Glendora
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores
Request your CCR — your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test — certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration — NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories — monitor your local utility website and local news for boil water advisories or system alerts
Contaminants Detected in Glendora Water Systems
The following contaminants have been detected or caused violations across Glendora's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Stage 1 DBP Rule | Treatment Technique | N/A | 2 | 2 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
EPA Enforcement History
The EPA and state regulators have taken 2 enforcement actions against water systems serving Glendora. Recent actions:
| Date | Action Type |
|---|---|
| 2022-08-03 | State Order Extension |
| 2021-10-26 | State Filed Suit |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2022-08-03.
Glendora vs. Nearby California Cities
How Glendora's water quality compares to similar cities in California:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Glendora | B | 2 | 1 | 49,934 |
| La Mirada | C | 0 | 1 | 49,954 |
| Poway | A | 0 | 1 | 49,888 |
| Colton | C | 6 | 4 | 49,425 |
Common Questions About Glendora Water
These are the most common questions residents search for about water quality in Glendora, California:
Is Glendora water hard or soft? Water hardness varies by source. Glendora's 1 water system uses a single source. Check your ZIP code report for specific hardness data.
Can I drink Glendora tap water? Glendora's water receives a grade of B (83/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Glendora? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Glendora vs. California Average
Understanding how Glendora compares to the broader California average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below — water quality can vary significantly even within Glendora.
ZIP Codes in Glendora
Glendora spans 2 ZIP codes. The ZIP with the lowest water quality score is 91740. Each ZIP code has its own water quality profile based on the specific water system serving that area. Check each ZIP code for detailed contaminant data, violation history, and system information.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Updated daily.
Frequently Asked Questions
Your Water is Safe — Here's How to Keep It That Way
Grade B is excellent news. Here's what proactive homeowners do to maintain water quality:
Annual Water Testing
EPA recommends annual testing even with clean water. Home test kits: $20-$50. Catches changes before they become problems.
Maintenance Filtration
A basic carbon filter removes chlorine taste and catches emerging contaminants like PFAS that aren't yet fully regulated.
Plumbing Check
Even safe city water picks up lead from home pipes. If your home was built before 1986, a one-time pipe inspection is recommended.