Where Does Your Water Come From

Like many water districts in south Orange County, El Toro Water District (ETWD) is nearly 100% dependent on imported water to meet the water needs of our customers. Our imported supply typically consists of a blend of water from the Colorado River and the Sacramento Bay Delta via the State Water Project. Both sources of import water are transported from hundreds of miles through a series of tunnels, aqueducts and pipelines to reach Orange County.

ETWD is a member agency of the Municipal Water District of Orange County (MWDOC), a wholesaler of imported water, which is purchased, transported and treated by the Metropolitan Water District of Southern California (MWDSC).

When the imported water supply reaches Southern California, it goes to the Diemer Filtration Plant, located in the City of Yorba Linda, to be purified and to ensure that it meets or exceeds all federal, state and local water quality regulations. From there the fully treated water is conveyed to south Orange County via two large pipelines called the Allen-McColloch Pipeline (AMP) and the East Orange County Feeder #2 Pipeline. The AMP ultimately traverses its way to ETWD’s largest reservoir, which is located in the City of Mission Viejo.

Given our dependence on imported water and the extensive delivery system, it is critical that ETWD maintains and creates local water supply resources that will sustain our daily water need.


El Toro Water District (District) has taken a leading role in improving local water supply reliability for south Orange County. Together with Santa Margarita Water District and Moulton Niguel Water District, the District maintains and operates the largest covered drinking water reservoir in all of Orange County – with a capacity of 275 million gallons. In the event of an emergency or unplanned interruption of water service, the reservoir would provide a 14 day supply of water to El Toro Water District customers.


Realizing that water resources in California are diminishing as the population increases, the El Toro Water District Board of Directors has committed the District to on-going cooperation and participation in regional partnerships to ensure that water service to our 51,000 customers remains reliable and economical for generations to come. Future water reliability will require continued financial investment in a diversified portfolio of water resources and infrastructure inclusive of but not limited to:

• Development of additional local and regional storage reservoirs
• Robust education in the areas of demand-side management/water use efficiency programs
• Innovative contractual arrangements for groundwater banking and agriculture to urban water transfers
• Expanded recycling of domestic wastewater for beneficial reuse
• Development of potential ocean desalination

For more information on water supply please refer to our “Important Links Page” section. Suggested sites: “Municipal Water District of Orange County”, “Association of California Water Agencies”, and “Metropolitan Water District of Southern California”.