Thousand Oaks Water Exceeds Standards

Every year, the City of Thousand Oaks (City) Public Works Department is required to prepare and provide the City of Thousand Oaks Water Agency customers with the Annual Water Quality Report, also known as the Consumer Confidence Report (CCR). Included in this report are details about where the City’s water comes from, its quality, and how it compares to State standards. The City works diligently with its neighbors, partners, and suppliers to continually improve the quality of the water supply, to protect its water sources, and improve the reliability of supply and the integrity of its storage and distribution system.

The Water Agency purchases and distributes as much as 15 million gallons of water each day to roughly 17,000 residences and businesses within the City’s water service area. Its mission is to provide high-quality water that meets the stringent water quality standards established by the U.S. Environmental Protection Agency (EPA) and the State Water Resources Control Board (SWRCB). Two other water purveyors provide service within the City. California Water Service provides service in the Westlake Village area, and California American Water provides service in Newbury Park and parts of Thousand Oaks. To view the service areas for all water purveyors, click HERE.

The 2025 CCR shows that the City’s water supply met or exceeded all State and Federal standards during the 2024 monitoring/sampling year.

Where does my water come from?

All of the City’s water supply (from all purveyors) comes from the State Water Project, either directly or indirectly. This water is imported from Northern California, originating at Lake Oroville where snow melt and runoff from the Sierra Nevada Mountains is collected and stored. The water then flows through the Sacramento River Delta system and transported via the California Aqueduct to Southern California. The water that is moved west to Ventura County is treated, filtered and disinfected at Metropolitan Water District’s (MWD) Jensen Filtration Plant in Granada Hills. In 2024, 98% of the City’s water supply came directly from the State Water Project. Thousand Oaks purchases its water from Calleguas Water District, the region’s water distributor. State Water Project water that is not immediately distributed by Calleguas is stored in Lake Bard at Calleguas’ headquarters in Thousand Oaks, or at their Los Posas Aquifer Storage and Recovery Wellfield (Wellfield). In 2024, 2% of the City’s water supply came from Lake Bard. These water supplies are then piped directly to the City through the Calleguas distribution pipes that connect to the City’s water system.

Should imported water sources be interrupted by general maintenance, earthquake or other emergency, Calleguas can deliver a limited amount of emergency water to the City from the Las Posas Wellfield and Lake Bard.

What can I learn from a Consumer Confidence Report?

1. Information: The report contains important information about the source of the City’s water, any detected contaminants, and compliance with federal drinking water standards. It may include details about the treatment processes, monitoring, and any violations or advisories issued during the reporting year.
2. Water Source(s): The report identifies the sources of the drinking water.
3. Contaminant Monitoring: The report provides a list of regulated and unregulated contaminants that were tested for in the drinking water supply. These can include bacteria, heavy metals, disinfection byproducts, pesticides, and other potential contaminants. It outlines the results of the tests, indicating whether the water met the required standards or if any violations occurred.
4. Health Effects and Compliance: The report explains the potential health effects of contaminants, particularly if any were found to exceed the maximum allowable levels. It should clearly state whether the water supplier met all federal drinking water standards or if any violations occurred during the reporting period.
5. Educational Information: The report may include educational material pertaining to public health.

The CCR aims to promote awareness and understanding of the quality of the drinking water supply. It allows consumers to make informed decisions about their water usage and take appropriate actions if necessary, such as installing additional water treatment systems or contacting the water supplier for further information.

To view the City’s 2025 Annual Water Quality Report, please visit www.toaks.co/waterqualityreport. If you would like a hard copy of the 2025 Annual Water Quality Report mailed to you or would like to speak with someone about the report, please call the Public Works Department at (805) 449-2499.

To view the water quality report for California American Water, click here, and for California Water Service, click here.