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Community Water System · PWS CA4100510

Redwood Terrace Mutual

La Honda, California 94020 - drinking water served from surface water sources to 56 people, tracked in EPA SDWIS and UCMR5.

56
People served
137
EPA violations
5
Health-based
Untested
UCMR5 result

The verdict

EPA records 137 drinking-water violations at Redwood Terrace Mutual, 4% of them health-based - above the California per-system average.

137
Total EPA violations on record
4%
Health-based (MCL / treatment failure)
56
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Redwood Terrace Mutual

Redwood Terrace Mutual is a private-owned community water system that delivers drinking water to 56 residents in La Honda, California (San Mateo County) through 18 service connections. Its water is drawn from surface water sources. EPA's Safe Drinking Water Information System records 137 total violations for this system , of which 5 (4%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 126 monitoring and reporting violations are on file. The most recent violation on record dates to 2024.

The most frequently cited contaminant at this system is Coliform (TCR), recorded in 10 violations (MR). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across California, EPA tracks 7,249 public water systems serving 42,404,883 people, with 153,308 cumulative violations and 63,983 health-based violations on record. About 89% of systems in the state carry at least one violation, and state-wide the average per system is 21.1 violations. Statewide, 447 of 694 UCMR5-tested systems have reported PFAS detections (64.4%).

Redwood Terrace Mutual's 137 violations sit above the California average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

Population Served
56
Total Violations
137
Health-Based Violations
5
Water Source
Surface Water

System Details

System Type
Community
Owner Type
Private
Connections
18
County
San Mateo
School/Daycare
No
MCL Violations
3
Monitoring Violations
126
Treatment Tech Violations
2

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Coliform (TCR) MR 10 2010
Radium-228 MR 4 2009
1,2-Dichloroethane MR 2 2009
Vinyl chloride MR 2 2009
Trichloroethylene MR 2 2009
Xylenes, Total MR 2 2009
TTHM MR 2 2009
Carbon tetrachloride MR 2 2009
Tetrachloroethylene MR 2 2009
1,1,2-Trichloroethane MR 2 2009
1,2,4-Trichlorobenzene MR 2 2009
cis-1,2-Dichloroethylene MR 2 2009
Styrene MR 2 2009
Benzo(a)pyrene MR 2 2009
2,3,7,8-TCDD MR 2 2009
Dalapon MR 2 2009
Pentachlorophenol MR 2 2009
2,4,5-TP MR 2 2009
Di(2-ethylhexyl) phthalate MR 2 2009
BHC-GAMMA MR 2 2009
Chlordane MR 2 2009
Endrin MR 2 2009
Heptachlor epoxide MR 2 2009
Total Polychlorinated Biphenyls (PCB) MR 2 2009
HEXACHLOROBENZENE MR 2 2009
Diquat MR 2 2009
Carbofuran MR 2 2009
Lead and Copper Rule MR 2 2024
Revised Total Coliform Rule TT 2 2019
Gross Alpha, Excl. Radon and U MR 2 1981

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Redwood Terrace Mutual.

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID CA4100510 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

California Drinking Water Authority

California State Water Resources Control Board, Division of Drinking Water is the primacy agency that licenses and inspects Redwood Terrace Mutual under EPA-delegated authority.

Open CA regulator portal

Source: California State Water Resources Control Board, Division of Drinking Water

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2024 Lead and Copper Rule MR 2 SDWIS / CA4100510 / 5000
2019 Revised Total Coliform Rule TT 2 SDWIS / CA4100510 / 8000
2019 Nitrate-Nitrite MR 2 SDWIS / CA4100510 / 1038
2010 Coliform (TCR) MR 10 SDWIS / CA4100510 / 3100
2009 Radium-228 MR 4 SDWIS / CA4100510 / 4030
2009 1,2-Dichloroethane MR 2 SDWIS / CA4100510 / 2980
2009 Vinyl chloride MR 2 SDWIS / CA4100510 / 2976
2009 Trichloroethylene MR 2 SDWIS / CA4100510 / 2984
2009 Xylenes, Total MR 2 SDWIS / CA4100510 / 2955
2009 TTHM MR 2 SDWIS / CA4100510 / 2950
2009 Carbon tetrachloride MR 2 SDWIS / CA4100510 / 2982
2009 Tetrachloroethylene MR 2 SDWIS / CA4100510 / 2987
2009 1,1,2-Trichloroethane MR 2 SDWIS / CA4100510 / 2985
2009 1,2,4-Trichlorobenzene MR 2 SDWIS / CA4100510 / 2378
2009 cis-1,2-Dichloroethylene MR 2 SDWIS / CA4100510 / 2380

How Redwood Terrace Mutual Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Redwood Terrace Mutual California avg Federal benchmark
Total violations 137 21.1 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 5 8.8 Indicates a contaminant exceeded a federal MCL
PFAS detection None 64.4% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 56 5,850 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 7,249 regulated public water systems in California.

Federal MCL reference, Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Redwood Terrace Mutual water safe to drink? ▼
Redwood Terrace Mutual (PWS ID: CA4100510) has 137 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 56 people using Surface Water sources.
How many people does Redwood Terrace Mutual serve? ▼
Redwood Terrace Mutual serves 56 people in La Honda, California. It is a Private-owned system using Surface Water water sources with 18 service connections.
What type of violations does Redwood Terrace Mutual have? ▼
Redwood Terrace Mutual has 137 total violations: 5 health-based violations (MCL exceedances or treatment failures), 126 monitoring/reporting violations, and 2 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Redwood Terrace Mutual water? ▼
No PFAS testing data is available for Redwood Terrace Mutual under the EPA's UCMR5 monitoring program.
What water source does Redwood Terrace Mutual use? ▼
Redwood Terrace Mutual uses Surface Water as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. This data is provided for informational purposes only.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.