Water Quality in San Gregorio, CA: No Violations — Grade B
Grade B · Score 73/100 · 1 water system · Updated 2026-05-03
San Gregorio'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
What does the EPA compliance record show for San Gregorio, CA? Zero violations documented across 1 water system, with all health-based and monitoring thresholds met across all available federal records.
Water Quality by ZIP Code in San Gregorio
Water quality varies across San Gregorio's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 94074 | B | 73 | 0 | 0 | View report → |
Water Quality Overview
San Gregorio, California receives a water quality grade of B with an overall score of 73 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
No EPA violations have been recorded for the 1 water system serving San Gregorio. This is a positive indicator, though it does not guarantee the absence of all contaminants — some substances (like PFAS) are not yet fully regulated.
What Grade B Means
A grade of B indicates good compliance with EPA drinking water standards. While not perfect, San Gregorio'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
Lead testing data for San Gregorio is currently being collected. The EPA requires all community water systems to test for lead under the Lead and Copper Rule.
With 79% of homes built before 1986, San Gregorio 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.
Water Systems Serving San Gregorio
San Gregorio is served by 1 community water system regulated under the Safe Drinking Water Act. These systems collectively serve approximately 22,362 people across 1 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
How to Check Your Water in San Gregorio
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
San Gregorio vs. Nearby California Cities
How San Gregorio's water quality compares to similar cities in California:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| San Gregorio | B | 0 | 1 | 22,362 |
| Atherton | C | 0 | 1 | 22,362 |
| Marysville | B | 3 | 5 | 22,264 |
| Arcata | A | 0 | 3 | 22,549 |
Common Questions About San Gregorio Water
These are the most common questions residents search for about water quality in San Gregorio, California:
Is San Gregorio water hard or soft? Water hardness varies by source. San Gregorio's 1 water system uses a single source. Check your ZIP code report for specific hardness data.
Can I drink San Gregorio tap water? San Gregorio's water receives a grade of B (73/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for San Gregorio? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
San Gregorio vs. California Average
Understanding how San Gregorio 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 San Gregorio.
ZIP Codes in San Gregorio
San Gregorio spans 1 ZIP code. 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.