Journey of Water
LA County imports roughly two-thirds of its water from the Sierra Nevada in Northern California and the Colorado River. The remaining third comes from local supplies including water recycling, desalination, stormwater capture and groundwater. Hundreds of miles of aqueducts, reservoirs and basins, and a complex distribution system, are required to consistently deliver water to Southern California homes and businesses.
Explore how water moves from distant rivers and mountains through a vast system of pipelines, aqueducts, and treatment facilities.
From the Mountains and Rivers
The California State Water Project delivers
water to 27 million Californians through canals, pipelines, reservoirs, and hydroelectric power facilities. Along with water from the Colorado River, this water—known as imported water—is brought to Southern California by water wholesalers, which are responsible for sourcing, treating, and delivering water to their region.
Key wholesalers that serve LA County include the Metropolitan Water District of Southern California, Antelope Valley-East Kern Water Agency (AVEK), and Santa Clarita Valley Water Agency.
Moving Millions of Gallons
A large network of massive pipelines, reservoirs, and pumping plants spanning more than 400 miles moves water across Southern California. Some parts of the system rely on gravity, while others use energy‑intensive pumps to move water over mountains and across basins. This complex network ensures a steady and reliable supply every day of the year.
The Science That Keeps Our
Water Safe
Water is cleaned by local water providers
to meet strict water quality and safety
standards. California has some of the strictest water quality standards in the United States, ensuring the water that reaches your tap is safe to drink and use around your home.
The Final Stretch
Many retail water providers, like Los Angeles Department of Water & Power or Glendale Water & Power, rely on a combination of imported water supplies purchased from Metropolitan Water District of Southern California, and local water supplies such as groundwater. Retail water agencies use local distribution systems to deliver water directly to homes and businesses throughout Southern California, ensuring every drop is safe and clean.
The Story Behind Every Drop
Understanding water’s journey helps us appreciate the systems that keep our taps running and why both imported and local supplies matter. When we know the work behind every drop, we’re empowered to protect our water and support the investments that ensure long‑term reliability.
Follow The Journey
For a deeper look at how water moves across Southern California, explore Metropolitan Water District’s overview of the systems that supply our region.