City of Thousand Oaks Water Department
EPA ID: CA5610020 · 53,157 people served · 9 ZIP codes
Water monitoring for City of Thousand Oaks Water Department: clean, five years, 53,157 residents.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for City of Thousand Oaks Water Department Source: EPA SDWIS service area boundaries.
Service area boundary — Grade C
Service Area Demographics
The City of Thousand Oaks Water Department serves a community with a median household income of $146,766 and an estimated 192,234 residents across its service area. Approximately 63% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
City of Thousand Oaks Water Department'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 Ventura 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 61th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Comparable Water Systems
Similar-sized systems in California
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
CITY OF THOUSAND OAKS WATER DEPARTMENT (EPA ID: CA5610020) is a community water system in California that serves approximately 53,157 people from surface water sources.
This system provides water to 9 ZIP codes across 5 communities.
Average Home Safety Score: C (61/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
| ZIP Code | Lead Level | Exceeds Limit | Sample Date |
|---|---|---|---|
| 91358 | 0.0025 mg/L | No | N/A |
| 91360 | 0.0025 mg/L | No | N/A |
| 91362 | 0.0025 mg/L | No | N/A |
| 91363 | 0.0025 mg/L | No | N/A |
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 1 (High 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
Coverage: 5 ZIP codes confirmed via EPA Community Water System Service Area Boundaries v3 plus 4 additional ZIPs inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
- 91319 — Newbury Park
- 91320 — Newbury Park
- 91358 — Thousand Oaks
- 91360 — Thousand Oaks
- 91361 — Westlake Village
- 91362 — Thousand Oaks
- 91363 — Thousand Oaks
- 91377 — Oak Park
- 93021 — Moorpark
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for City of Thousand Oaks Water Department (CA5610020) on EPA.gov.
Frequently Asked Questions
Is City of Thousand Oaks Water Department water safe to drink?
Based on EPA records, City of Thousand Oaks Water Department has no recorded violations in the past 5 years — a positive indicator of water quality management.
How many people does City of Thousand Oaks Water Department serve?
City of Thousand Oaks Water Department serves approximately 53,157 people across 9 ZIP codes in California.
Where does City of Thousand Oaks Water Department 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 City of Thousand Oaks 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: City of Thousand Oaks Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility. Treatment and source data are sourced from the utility's published CCR filings.
State Water Project supplies are most vulnerable to urban/stormwater runoff, wildlife, agriculture, recreation, and wastewater.
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 City of Thousand Oaks 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.
Federal UCMR5 PFAS Monitoring: Tested Clean
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were detected.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Lead Service Line Replacement Tracker
This water utility's lead service line (LSL) replacement program is tracked from public Consumer Confidence Report filings. Email signup notifies subscribers when the utility files an updated replacement plan or progress milestone.
City of Thousand Oaks
ZipCheckup is not affiliated with this water utility. LSL replacement-program data is sourced from public CCR filings published by the utility. Subscription notifications are based on automated parsing of subsequent CCR releases.
Learn more about Lead and Copper Rule replacement requirements →
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 City of Thousand Oaks 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 City of Thousand Oaks
Your utility reported water hardness of 148 ppm CaCO₃ (8.65 grains per gallon) in its most recent Consumer Confidence Report. This is in the moderately 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.
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
City of Thousand Oaks Water Department (EPA ID: CA5610020) — request the latest Consumer Confidence Report or ask about specific contaminants.