Purifying Sewage for Drinking Water

In response to drought conditions, a new water purification system will make sewage water drinkable for CA communities. Learn the details of the multi-step purification process

What Happened?

The Silicon Valley Advanced Water Purification Center in Santa Clara County is designed to help curb water shortage issues by treating sewage water to make it drinkable. The wastewater treatment plant uses a multi-step system to recycle water in light of prolonged drought conditions.


California has been combatting a drought for several years now. Santa Clara County now houses the Silicon Valley Advanced Water Purification Center to efficiently recycle wastewater into a higher quality than typical drinking water without depleting local resources. The high-tech purification plant cleanses used water through:
  • Microfiltration
  • Reverse osmosis
  • Ultraviolet rays

The water purification center produces 8 million gallons of water daily that is considered as pure as distilled water. The county uses the plant to improve the quality of water from older recycling systems and reintegrating the water back into a main source.

Currently the improved recycled water is used for irrigating crops and water green spaces, as well as cooling large commercial buildings. Moving forward, however, the plant is expected to feed into local taps by 2025. The persistent drought conditions may move that date up as water sources continue to lower.

How It Works

The Silicon Valley Advanced Water Purification Center treats wastewater to be used in the community rather than discharged into the San Francisco Bay. The 8 million gallons of highly purified water produced daily can match California’s primary drinking water standards. The three-step purification process includes:
  • Microfiltration Treated wastewater is forced through filtration membrane modules with thousands of holler fibers with very fine pores. Water is drawn through the pores into the center of the fibers eliminating bacteria, solids, protozoa and other unwanted items.
  • Reverse osmosis Water is pressed through membrane sheets with even smaller holes to remove constituents like salts and viruses.
  • Ultraviolet light As a final safeguard, water is sent through chambers that emit strong ultraviolet light to break down any remaining organic compounds. This is the same technique used to sterilize medicine and foods.

The benefits of the three-step purification process include:

  • Improved recycled water qualify
  • Locally controlled water supply
  • Increased water reliability
  • Reduced dependency on water from other sources
  • Protected groundwater supplies and nearby environment
  • Reduced wastewater discharge

The $72 million purification center is operated by the water district and the city of San Jose. The center has received $8.25 million from the federal American Recovery and Re-Investment Act, and $5.25 million from the California Department of Water Resources.

Demo Project

The Padre Dam Municipal Water District of California recently launched a new Advanced Water Purification Demonstration Project to showcase the capabilities of purification technologies to help communities meet drinking water demands despite drought conditions and rising cost of imported water.

The $3 million project will use advanced water purification technologies to diversify and increase the East County’s water supply. Wastewater will be purified through a four-step process: free chlorine disinfection, membrane filtration, reverse osmosis and ultraviolet oxidation.

Over the 12 month pilot period, the project will produce 100,000 gallons of purified water daily. If the project is successful the technology will be expanded to provide 3 million of water per day in to community’s water sources.

Value of Water Resources

Gov1 has reported on innovative uses of water as well as strategies to protect communities from unnecessary waste.

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