Thousand Oaks, CA: High Radon Risk — 70/100 (2026)
4 ZIP codes · 6 water systems · Updated 2026-06-03
Water systems serving Thousand Oaks hold a strong EPA compliance record — the city places among the better-performing areas in CA with few health-based violations on file.
How Thousand Oaks Compares
Data: EPA SDWIS Last verified: 2026-06-03
Key Facts for Thousand Oaks Residents
- Average lead level: 0.0025 mg/L.
- Estimated remediation: $1,800 per household.
- CDC health risk index: 10.81.
Thousand Oaks's Water Providers
In Thousand Oaks, CA, residential water supply is distributed across multiple utilities rather than concentrated in one. The 3 leading providers out of 6 tracked systems each control their own infrastructure, file separate EPA compliance reports, and set independent rate schedules.
Overview
We track water quality and home safety data for 4 ZIP codes in Thousand Oaks, California (population ~78,520), covering 6 community water systems serving approximately 320,006 people region-wide.
No EPA violations recorded across any ZIP codes in Thousand Oaks — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Thousand Oaks: B (70/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Thousand Oaks water systems draw from: Surface water.
Lead & Copper
- Average lead level (90th percentile): 0.0025 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 1 (High Risk)
- Zone 1 (High): 3 ZIP codes
- Zone 2 (Moderate): 1 ZIP code
- Zone 3 (Low): 0 ZIP codes
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 91358 | C | City of Thousand Oaks Water Department | 53,157 |
| 91360 | C | City of Thousand Oaks Water Department | 53,157 |
| 91362 | C | City of Thousand Oaks Water Department | 53,157 |
| 91363 | B | City of Thousand Oaks Water Department | 53,157 |
All ZIP Codes in Thousand Oaks
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
Updated daily.
Thousand Oaks Community Health Snapshot
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
How Remediation Costs Compare in Thousand Oaks
When remediation costs are measured against Thousand Oaks home values, the resulting ratio is in the low tier — addressing documented water and safety issues here claims only a minor fraction of typical equity, and most homeowners are in a position where the financial commitment is straightforward rather than a material burden on their household budget.
Remediation costs in Thousand Oaks are relatively low compared to home values. The $1,200–$2,400 estimated range is a small fraction of median property value. Home values are 46% above the California average.
Thousand Oaks: Lead Risk & Vulnerable Populations
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
Lead risk in Thousand Oaks appears low overall, but individual homes may differ. Testing is the only way to confirm your water's lead content.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Thousand Oaks: Flood History & Water Damage Risk
Multiple flood events have been recorded for Thousand Oaks through the NFIP — 45 claims in total, with 50% of ZIP codes in FEMA-designated zones — pointing to a flood exposure profile that merits inclusion in a water quality assessment without reaching high-severity planning territory.
Thousand Oaks has a moderate flood history with 45 FEMA claims averaging $5,490 per payout. 50% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$1,800</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
Deep Dive Reports
Detailed analysis for Thousand Oaks, CA