How water works in Orange County

The water cycle in Orange County, California, does not just involve water evaporating from Earth’s surface, rising into the atmosphere, cooling and condensing into rain or snow in clouds, and then falling again to the surface as rain.  If the region relied solely on this natural water cycle, there would not be enough water to meet the needs of its 3 million residents and businesses.

North and central O.C.

The Orange County Water District (OCWD), servicing north and central Orange County, refills the Orange County Groundwater Basin with many different water supplies: water from the Santa Ana River, which includes rainfall, snowmelt and treated wastewater from upstream water users; local rainfall; and imported water from the Colorado River and Northern California. Additionally, OCWD supplements Mother Nature’s limited water supplies with water that used to be wastewater.

About 200 million gallons per day of wastewater, from more than 2.5 million customers, is sent to the Orange County Sanitation District (OCSD), where it is treated. Some of the treated wastewater is discharged into the Pacific Ocean, but about 130 million gallons of it is sent to OCWD’s Groundwater Replenishment System (GWRS) where it is purified to exceed drinking water standards. The GWRS water is then put back into the basin where it blends with all the other water supplies and is ultimately reused again, and again and again.

Thanks to OCWD’s innovative water management program, north and central Orange County communities can pump about 75 percent of their water demands from the basin without causing damage to this large aquifer. They get the remaining 25 percent of their needs from imported supplies. The Metropolitan Water District of Southern California (MWD) supplies the imported water through it local subsidiary member agency, the Municipal Water District of Orange County (MWDOC). Nineteen retail water agencies and city water departments deliver a blend of these waters to north and central Orange County residents and businesses.

South O.C.

The remaining 600,000 customers living in cities located in south Orange County, do not reside within the boundaries of the Orange County Groundwater Basin and are heavily dependent on Mother Nature.  Ninety percent of their water supply is imported from hundreds of miles away. They only get about 10 percent of their water from small groundwater basins, found in that part of the county, and some local water recycling projects used for irrigation. Seven retail water agencies and city water departments deliver water to south Orange County residents and businesses.

O.C. retail water agencies

Retail water agencies establish the price of water delivered to customers. The rate charged for water is impacted by multiple factors, including the cost of groundwater; the cost of imported water; the cost to construct, operate and maintain pipelines, reservoirs and pumps to deliver water to homes or businesses; and the administrative cost of operating a retail water system. Retailers' rates can vary depending upon the age of the water system, how much groundwater is used versus more expensive imported water, and other factors. For this reason, OCWD attempts to maximize the amount of groundwater available to retail agencies, while sustainably managing the basin.

South Orange County is more vulnerable during times of drought and pays almost three times as much for its water than residents in north and central Orange County. However, south Orange County communities are looking to make more investments in local projects like water recycling to help close the gap.    

View the Orange County water cycle graphic