Your Drinking Water

Santa Margarita Water District –SMWD—is proud to deliver 10 billion gallons of high-quality drinking water every year to more than 200,000 residents.

Like much of south Orange County, most of our drinking water is imported from hundreds of miles away. A sophisticated system of aqueducts, reservoirs, treatment plants and pipelines deliver water from northern California and the Colorado River to our customers.

To reduce our dependence on imported water, SMWD set a strategic goal to have a 30% local water supply by 2030. Why 30% you may ask? That's the amount of water required to meet critical indoor water needs in the event of an emergency that may cut off imported water supplies. Recycled water and desalination are key to reaching this goal.

Regardless of the source, every drop of drinking water complies with stringent water quality standards set by the U.S. Environmental Protection Agency and the State Water Resources Control Board.

Water Quality

Simple fact: Your drinking water is safe and clean.

SMWD is committed to delivering high-quality drinking water to every customer. Our dedicated team of laboratory professionals monitor the drinking water from 100 sites throughout the service area and run over 50,000 water quality tests each year. SMWD’s laboratory is certified by the California Environmental Laboratory Accreditation Program.

Additionally, SMWD’s wholesaler, the Metropolitan Water District of Southern California (MET) tests the water hundreds of thousands of times each year before delivering it to our region.

We’re also commitment to transparency with customers. With that in mind, SMWD holds a monthly meeting called the Water Quality and Treatment Committee to discuss all items related to water quality. The public is welcome to attend. SMWD also produces an annual Water Quality Report to share the results of the extensive water quality tests performed throughout the previous calendar year.

How does SMWD get its drinking water?

Water is delivered to our customers through a sophisticated system of aqueducts, reservoirs, treatment plants, and pipelines.

SMWD imports its drinking water through the Municipal Water District of Orange County (“MWDOC”) which represents 32 water providers in Orange County and is a member of the larger wholesaler, MET.

Met imports water for SMWD customers along with 9 million other people in southern California to the tune of 1.5 billion gallons per day. The water comes from the Colorado River Aqueduct and the State Water Project.

The Colorado River Aqueduct is a 242-mile system comprised of an open canal, tunnels, and siphons that carry millions of gallons of water a day from the Colorado River across the desert to the people of Southern California. The engineering marvel was built in the 1930s, as the nation was emerging from the Great Depression, and immediately became an essential element in creating the vibrant Southern California we know today.

The State Water Project spans more than 700 miles from the Sacramento-San Joaquin Delta in northern California to southern California. It is operated and maintained by the California Department of Water Resources.

In turn, Santa Margarita Water District delivers drinking water provided from three treatment plants:

Robert B. Diemer Treatment Plant
- Located in Yorba Linda and operated by the Metropolitan Water District of Southern California
- Typically fed with a blend of State Water Project and Colorado River Aqueduct water depending on regional conditions
Baker Water Treatment Plant
- SMWD is a partner in the regional treatment plant
- Located in Lake Forest and operated by Irvine Ranch Water District
- Fed by the Colorado River Aqueduct but can be fed with local Irvine Lake in the event of an emergency
San Juan Ground Water Plant
- Owned and operated by SMWD as of Nov. 2021
- Located in San Juan Capistrano
- Fed by local groundwater
- Capacity to treat 4 million gallons per day

The treated drinking water from these plants is sent through large transmission pipelines into the SMWD distribution system where it is delivered to homes, schools, and businesses.

Investing in Our Water Supply

For decades SMWD has strategically focused on projects that help reduce its dependence on imported drinking water and allow for local control of its water supply. It is no small feat when there is limited groundwater in the region. It’s a delicate balance of demand management through conservation and recycling water, building infrastructure to store water locally, and investing in alternative supply projects like desalination, to exploring innovative ideas.

Here's a look at some key projects:

Most recently, SMWD expanded its services to San Juan Capistrano. In 2021, SMWD annexed the drinking water, wastewater and recycled water services in San Juan Capistrano which included a groundwater treatment plant – SMWD’s first groundwater plant.
In 2020, Orange County’s largest recycled water reservoir was completed after 15 years of planning, design and construction. The Trampas Canyon Reservoir holds 1.6 billion gallons of recycled water for watering common areas and may one day be a source of local drinking water.
In 2016, Lake Mission Viejo became California’s first swimming lake to use advanced treated water, saving some 98 million gallons of drinking water each year.
In 2011, the regions first emergency drinking water storage reservoir, Upper Chiquita Reservoir was completed. It holds 244-million-gallons of fresh drinking water and can provide up to 168,000 families with 200 gallons of fresh drinking water for one week. SMWD led the regional effort to provide drinking water in the event of water disruptions due to a natural disaster or other emergency.
SMWD also maintains the South County Pipeline, the primary pipeline that transports water to much of south Orange County.
- 24 miles long
- Pipe diameters range from 4”" to 66”
- Each year, this pipeline moves 9 billion gallons of drinking water that supplies SMWD and neighboring communities