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Community Water System · PWS CA4300575

Twin Valley Inc

Castroville, California 95012 - drinking water served from groundwater sources to 317 people, tracked in EPA SDWIS and UCMR5.

317
People served
129
EPA violations
80
Health-based
Untested
UCMR5 result

The verdict

EPA records 129 drinking-water violations at Twin Valley Inc, 62% of them health-based - above the California per-system average.

129
Total EPA violations on record
62%
Health-based (MCL / treatment failure)
317
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Twin Valley Inc

Twin Valley Inc is a private-owned community water system that delivers drinking water to 317 residents in Castroville, California (Santa Clara County) through 96 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 129 total violations for this system , of which 80 (62%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 34 monitoring and reporting violations are on file. The most recent violation on record dates to 2023.

The most frequently cited contaminant at this system is Nitrate, recorded in 72 violations (MCL, health-based). 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%).

Twin Valley Inc's 129 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
317
Total Violations
129
Health-Based Violations
80
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Private
Connections
96
County
Santa Clara
School/Daycare
No
MCL Violations
80
Monitoring Violations
34
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Nitrate MCL 72 2023
Coliform (TCR) MCL 8 2015
Coliform (TCR) MR 8 2015
Lead and Copper Rule MR 5 2007
Revised Total Coliform Rule MON 5 2018
Groundwater Rule MR 4 2015
Asbestos MR 2 1993
Gross Alpha, Excl. Radon and U MR 2 1981
Nitrate MR 2 2016
TTHM MR 2 2009
E. COLI MR 2 2012
Chlorine MR 2 2011

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 Twin Valley Inc.

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 CA4300575 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 Twin Valley Inc 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
2023 Nitrate MCL 72 SDWIS / CA4300575 / 1040
2018 Revised Total Coliform Rule MON 5 SDWIS / CA4300575 / 8000
2016 Nitrate MR 2 SDWIS / CA4300575 / 1040
2015 Coliform (TCR) MCL 8 SDWIS / CA4300575 / 3100
2015 Coliform (TCR) MR 8 SDWIS / CA4300575 / 3100
2015 Groundwater Rule MR 4 SDWIS / CA4300575 / 0700
2012 E. COLI MR 2 SDWIS / CA4300575 / 3014
2011 Chlorine MR 2 SDWIS / CA4300575 / 0999
2009 TTHM MR 2 SDWIS / CA4300575 / 2950
2007 Lead and Copper Rule MR 5 SDWIS / CA4300575 / 5000
1993 Asbestos MR 2 SDWIS / CA4300575 / 1094
1981 Gross Alpha, Excl. Radon and U MR 2 SDWIS / CA4300575 / 4000

How Twin Valley Inc Compares

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

Metric Twin Valley Inc California avg Federal benchmark
Total violations 129 21.1 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 80 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 317 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 Twin Valley Inc water safe to drink? ▼
Twin Valley Inc (PWS ID: CA4300575) has 129 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 317 people using Groundwater sources.
How many people does Twin Valley Inc serve? ▼
Twin Valley Inc serves 317 people in Castroville, California. It is a Private-owned system using Groundwater water sources with 96 service connections.
What type of violations does Twin Valley Inc have? ▼
Twin Valley Inc has 129 total violations: 80 health-based violations (MCL exceedances or treatment failures), 34 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Twin Valley Inc water? ▼
No PFAS testing data is available for Twin Valley Inc under the EPA's UCMR5 monitoring program.
What water source does Twin Valley Inc use? ▼
Twin Valley Inc uses Groundwater 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.