Process steps

  1. 1

    Pre-purification

  2. 2

    Microfiltration

  3. 3

    Reverse osmosis

  4. 4

    Ultraviolet light

  5. 5

    Water delivery

Water delivery

Play H2O Delivery

Where does the water go?

The GWRS has a current production capacity of 100 million gallons (379,000 cubic meters; 307 acre-feet) of water per day and a total production of 36.5 billion gallons (138 million cubic meters; 112,000 acre-feet) per year. After water is treated with the three step process at the GWRS, approximately 35 million gallons (132,500 cubic meters) of GWRS water per day are pumped into injection wells where it serves as a seawater intrusion barrier. Another 65 million gallons (246,000 cubic meters) per day are pumped to recharge basins in Anaheim, where GWRS water filters through sand and gravel to replenish the deep aquifers of north and central Orange County’s groundwater basin.

Seawater Barrier

The threat of salt water from the ocean contaminating Orange County's groundwater basin has been a concern for decades. The groundwater basin is the county's primary potable water supply and provides storage for nearly 500,000 acre-feet (616,000 cubic meters) of usable water. As the region has continued to grow, water demands have risen. Pumping more water out of the basin increases the possibility of salt water seeping into the basin.

Seawater barrier illustration

The Orange County Water District (OCWD) built Water Factory 21 (WF-21) in the mid-1970s to treat wastewater to inject into 23 wells along the coast, creating a seawater intrusion barrier. As demands to pump more water out of the basin increased, the barrier required more purified water than WF-21 could produce, which had a daily production of 22.6 million gallons (85,600 cubic meters) per day. [14 million gallons (53,000 cubic meters) of WF-21 water blended with 8.6 million gallons (32,600 cubic meters) of deep well water.]

With the completion of the GWRS, OCWD now produces enough water to form a highly protective barrier that safeguards Orange County's fresh water supply. About one-third of the water produced by GWRS (35 million gallons; 132,000 cubic meters) is injected into the seawater intrusion barrier every day.

Groundwater Recharge

The Orange County Water District (OCWD) is responsible for managing a very large groundwater basin that provides approximately 75 percent of the potable water supply for more than 2.5 million residents of north and central Orange County.

In 1936, OCWD began purchasing portions of the Santa Ana River channel to actively manage capture of the river water as a source of supply for the groundwater basin. Today, OCWD owns approximately 1,000 acres contained within a six-mile section of the Santa Ana River from Imperial Highway to Ball Road in Anaheim, California. There are more than two dozen recharge basins in this area that range in depth from five to 150 feet (1.5 to 45 meters).

After water is purified through the GWRS, about two-thirds of it is pumped in a 13-mile (21 kilometers) pipeline to two of OCWD’s recharge basins, Kraemer and Miller, in Anaheim. The GWRS water percolates through the sand and gravel in these basins and naturally filters into the county’s groundwater basin. This groundwater is pumped from over 400 wells operated by local water agencies, cities and other groundwater users. The GWRS is an important and effective way to replenish the groundwater basin.