A97/100
Thousand Oaks Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 53,157 residents · California
What's In Thousand Oaks's Tap Water?
77
Contaminants Tested
1
Exceed EPA Limits
0
Above EPA Goals
1 contaminant above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 287.00 mg/L | 1.30 mg/L | Over Limit |
EPA Violation History
No violations in the past 5 years
This system has a clean compliance history.
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Water Utility Details
CITY OF THOUSAND OAKS WATER DEPARTMENT
Population Served
53,157
Water Source
Purchased Surface Water
System ID
CA5610020
Frequently Asked Questions About Thousand Oaks Water
Is Thousand Oaks tap water safe to drink?
Thousand Oaks, California tap water receives a grade of A (97/100), which is considered excellent. Out of 77 contaminants tested, 1 exceed EPA maximum contaminant levels (MCLs) and 1 exceed health guidelines (MCLGs). While the water meets federal standards, some residents may still choose to use a filter for additional peace of mind.
What contaminants are in Thousand Oaks's water?
Of the 77 contaminants tested in Thousand Oaks's water supply, the most notable include Copper (90th percentile). 1 contaminant(s) exceed EPA legal limits (MCLs). 1 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.
Does Thousand Oaks have any water quality violations?
No, Thousand Oaks has zero EPA violations on record. This means the water utility has consistently met all federal drinking water standards during the compliance periods tracked by the EPA.
Do I need a water filter in Thousand Oaks?
Based on EPA data, using a water filter in Thousand Oaks is recommended. 1 contaminant(s) exceed legal limits. An NSF-certified filter — such as a reverse osmosis or activated carbon system — can effectively reduce many common contaminants. Choose a filter certified to remove the specific contaminants found in your area.
Where does Thousand Oaks's tap water come from?
Thousand Oaks's drinking water is sourced from purchased surface water and supplied by CITY OF THOUSAND OAKS WATER DEPARTMENT. The system serves approximately 53,157 people. Surface water sources include rivers, lakes, and reservoirs.
How often is Thousand Oaks's water tested?
Under the Safe Drinking Water Act (SDWA), water utilities are required to regularly test for over 90 contaminants. Testing frequency varies by contaminant — some are tested monthly, others quarterly or annually. Thousand Oaks's water systems must report results to the EPA and publish an annual Consumer Confidence Report (CCR). The data on this page reflects the latest available EPA testing data.
How does Thousand Oaks's water compare to other cities in California?
Thousand Oaks's water quality score of 97/100 earns a grade of A, which is considered excellent. This places Thousand Oaks among the better-performing water systems in California. Visit our California state page to see how all cities in the state compare.
What should I do if I'm concerned about Thousand Oaks's water quality?
If you have concerns about Thousand Oaks's tap water, consider these steps: (1) Request your utility's annual Consumer Confidence Report for detailed local data. (2) Get your water independently tested through a state-certified laboratory. (3) Consider an NSF-certified water filter rated for the contaminants found in your area. (4) Contact your water utility (CITY OF THOUSAND OAKS WATER DEPARTMENT) with specific questions. (5) Report water quality issues to your state drinking water program or the EPA Safe Drinking Water Hotline at 800-426-4791.