Brackish Groundwater Desalination

h2oaks building

Using a previously untapped resource for the benefit of the entire region

San Antonio’s new desalination plant is officially up and running, pumping salty (brackish) water from nearly 1,500 feet underground in the Wilcox Aquifer and treating it to produce 12 million gallons of drinking water each day.

More than 10 years in the making, the H2Oaks Center is located in far south Bexar County at the site formerly known as SAWS Twin Oaks Aquifer Storage and Recovery. The location is now home to three water supplies, all operated from the H2Oaks control room: desalinated water, aquifer storage and recovery, and local Carrizo Aquifer.

  • Desalination adds yet another supply to the SAWS water portfolio, further reducing dependence on the drought-sensitive Edwards Aquifer.
  • The plant can produce 12 million gallons per day (13,441 acre-feet* per year) of finished water — enough to supply up to 53,000 households.
  • Desalinated water is plentiful and unaffected by drought conditions.

The Desal Process

desal plant testingDesalination uses a filtering process called reverse osmosis that removes 99.9 percent of the salts and minerals from the water. Once treated, the water tastes the same as Edwards Aquifer water and blends with the rest of the water in our system.

Every 10 gallons of brackish water is converted to nine gallons of drinking water. The salts and minerals that are removed are then injected deep into the ground into an area where existing salt concentrations are higher.

  • Raw, brackish water comes from the Wilcox Aquifer about 1,500 feet below the surface. That’s twice the height of the Tower of the Americas in downtown San Antonio.
  • More than 10 miles of pipelines transport the raw water to the plant for treatment.
  • Injection wells used to dispose of the concentrate/brine are more than a mile deep.

Click to view larger diagram

The facility includes 12 production wells and two injection wells, in addition to a water testing laboratory and treatment processing area. A visitor center gives guests an up-close-and-personal look at various areas of the plant, including the control room, lab and water treatment facilities.

  • The public spaces are created around the theme of “The Water Cycle,” to introduce guests to the story of SAWS.
  • An onsite research facility will be used by universities to study ways to optimize the desalination process and water supplies.
  • The plant was also designed to allow for easy expansion in the future.

Click to get a 360 view of SAWS Desalination plant in the final construction phase.

* An acre-foot of water is equivalent to 325,851 gallons