Cuesta La Honda Guild Inc.
EPA ID: CA4110012 · 915 people served · 1 ZIP code
Even though Cuesta La Honda Guild Inc. accumulated 5 violations over five years, all have been formally resolved — the provider currently meets EPA standards for 915 people.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Cuesta La Honda Guild Inc. Source: EPA SDWIS service area boundaries.
Service area boundary — Grade B
Service Area Demographics
The Cuesta La Honda Guild Inc. serves a community with a median household income of $250,001 and an estimated 1,745 residents across its service area. Approximately 75% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
Cuesta La Honda Guild Inc.'s water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 1% of homes in San Mateo County, California rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Superfund Proximity Note: This service area ranks in the 60th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Detected Contaminants
How Cuesta La Honda Guild Inc. compares to EPA limits
What This Means For You
Total Trihalomethanes (TTHM) at 4 mg/L exceeds the EPA maximum of 0.08 mg/L. Bladder & rectal cancer risk; reproductive concerns. Consider granular activated carbon (GAC) filtration.
E. coli at 1 Zero tolerance (any positive sample triggers immediate action) exceeds the EPA maximum of Zero tolerance (any positive sample triggers immediate action). Severe GI illness; potentially fatal kidney failure in children. Consider UV disinfection (99.99%) filtration.
Total Trihalomethanes (TTHM) was detected in this water system. granular activated carbon (GAC) filtration can reduce exposure.
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Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
Cuesta La Honda Guild Inc. (EPA ID: CA4110012) is a community water system in California that serves approximately 915 people from surface water sources.
This system serves ZIP code 94020 in La Honda.
Average Home Safety Score: B (74/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| March 1, 2024 | E. coli | Monitoring | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 4 | Yes |
| E. coli | Microbiological | 1 | No |
Health Risk Details
Total Trihalomethanes (TTHM) (EPA limit: 0.08 mg/L)
Bladder & rectal cancer risk; reproductive concerns At-risk groups: pregnant women, long-term consumers of chlorinated water, people who frequently shower in chlorinated water.
Removal methods: granular activated carbon (GAC), carbon block filter, point-of-entry aeration. Find the right filter →
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
| ZIP Code | Lead Level | Exceeds Limit | Sample Date |
|---|---|---|---|
| 94020 | 0.00039 mg/L | No | N/A |
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 2 (Moderate Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
- 94020 — La Honda
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Cuesta La Honda Guild Inc. (CA4110012) on EPA.gov.
Frequently Asked Questions
Is Cuesta La Honda Guild Inc. water safe to drink?
Cuesta La Honda Guild Inc. has recorded 4 health-based violations in the past 5 years. While the system is required to treat water to meet federal standards, you may want to consider additional precautions such as a certified water filter.
How many people does Cuesta La Honda Guild Inc. serve?
Cuesta La Honda Guild Inc. serves approximately 915 people across 1 ZIP code in California.
Where does Cuesta La Honda Guild Inc. get its water?
The primary water source is surface water.
Contact Your Water Utility
Public-record contact information for the water utility serving this system. Use these channels to request water quality reports, ask about service, or report issues directly.
Contact information from Cuesta La Honda Guild Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility, does not act as its agent, and does not provide customer support for it. Contact details shown are public-record information from CCR filings. For service issues, contact the utility directly using the information above.
Water Source & Treatment
Where this water originates and how it's treated before reaching your tap.
Source: Cuesta La Honda Guild Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility. Treatment and source data are sourced from the utility's published CCR filings.
An assessment of the drinking water source(s) for Water System #4110012, Cuesta La Honda, was completed for Lower Woodhams Creek in October 2011; Upper Woodhams Creek and Mindego Creek in March 2003. Upper Woodhams and Mindego Creeks are considered the most vulnerable to agricultural practices, storm water runoff, and animal husbandry activities. Additional testing included Glyphosate and Diquat (none detected), Cryptosporidium and Giardia (minimal detection), Aluminum and Iron (detected in raw water, treated water non-detect). Assessments are available at RealManage Office upon request.
Treatment regime
How this utility classifies its treatment process and what each reported treatment chemical does.
Treatment chemicals and what each one does
Chemical names are reported verbatim by the utility. Purpose categories are ZipCheckup annotations based on standard drinking-water treatment practice.
Watershed exposure sources reported
Land-use and natural conditions identified in the utility's source-water assessment as potential contamination sources upstream of treatment.
Treatment classification and chemical list sourced from Cuesta La Honda Guild Consumer Confidence Report.
Treatment intensity is a ZipCheckup-derived classification based on the chemicals and processes the utility reports. Chemicals and contamination sources are taken verbatim from the utility's CCR filing. Routine federal monitoring and contaminant testing shown elsewhere on this page determine whether the water meets safety standards, not the treatment classification.
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
This system reports zero confirmed lead service lines in its inventory. Unknown-material counts may still warrant verification.
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
Aesthetic water quality
These measurements describe the look, taste, and feel of the water this utility delivers. They are not contaminant violations — they sit alongside federal Secondary Maximum Contaminant Levels (SMCLs) which the EPA publishes as non-enforceable guidance.
Aesthetic measurements from Cuesta La Honda Guild Consumer Confidence Report.
Aesthetic measurements are reported by the utility from its annual sampling. EPA Secondary MCLs are advisory thresholds — values outside them indicate aesthetic concerns such as taste or appearance, not health violations. Federal contaminant testing is shown in the sections above.
Hard water detected in Cuesta La Honda Guild
Your utility reported water hardness of 391 ppm CaCO₃ (22.8 grains per gallon) in its most recent Consumer Confidence Report. This is in the very hard range and may cause scale buildup, reduced appliance lifespan, and dry skin or hair.
There are three common approaches to treating hard water: salt-based ion-exchange softeners (most effective, require salt refills), salt-free conditioners (lower maintenance, scale prevention only), and reverse osmosis at the kitchen sink (cooking and drinking water only). Aquasana, EcoWater, Pelican, and SpringWell are among the major US brands.
Paid Partner. ZipCheckup earns commission on Aquasana purchases. We do not test water or verify product effectiveness for specific hardness levels — manufacturer claims are theirs alone. Consult a certified water-quality professional for personalized advice.
Hardness data parsed from this utility's most recent Consumer Confidence Report. Severity bands per USGS hard water classification.
Notable events and violations
This section summarizes events the utility chose to disclose in its most recent Consumer Confidence Report, plus any federal compliance violations the utility recorded against itself. Both lists are utility-authored — ZipCheckup does not audit, judge, or reorder them.
Federal compliance violations on record
These entries are taken verbatim from the utility's CCR violations section. EPA defines four broad violation categories: Maximum Contaminant Level (MCL), Treatment Technique (TT), Monitoring & Reporting (M&R), and Public Notification (PN).
-
MCL · Haloacetic Acids (HAA5)2012-04-24
Water system failed to comply with the Haloacetic Acid maximum contaminant level based on the Running Annual Average throughout 2012.
-
monitoring · Routine Bacteriological2012-05
Failure to meet monitoring requirement for the month of May 2012.
-
monitoring · Routine Bacteriological2012-12
Failure to meet monitoring requirement for the month of December 2012.
-
treatment technique2012-Q1
Water Treatment failed to remove adequate Disinfection ByProducts (DBP) precursors and exceeded the HAA5 Maximum Contaminant Level (60 ppb) during Q1 2012.
Violations record from Cuesta La Honda Guild Consumer Confidence Report.
Notable events from the utility's CCR
These bullet entries are the utility's own narration of operational, regulatory, or infrastructure events during the reporting period.
- Giardia detected in Bobcat Reservoir (2010-2011)
- Haloacetic Acids MCL violation issued citation 02-17-12C-015
- Bacteriological monitoring violations (May 2012, December 2012)
- Disinfection byproducts precursors exceeded MCL in Q1 2012
ZipCheckup note: items above reflect what the utility published in its most recent CCR. Federal violation records are also tracked separately by the EPA Safe Drinking Water Information System (SDWIS) — the SDWIS record is the authoritative federal source for any specific regulatory action.
Frequently Asked Questions
What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
Cuesta La Honda Guild Inc. (EPA ID: CA4110012) — request the latest Consumer Confidence Report or ask about specific contaminants.