The Montevina Water Treatment Plant is one of the primary water supply sources for the Town of Los Gatos and the surrounding West Valley Communities. It produces about 10% of the total water supply for the San Jose Water, the South Bay’s largest water retailer. As a result, it is a crucial piece of our water supply to the community.

And as with any technology, upgrades are necessary from time-to-time.

After all, you wouldn’t want to drive your dad’s Plymouth Reliant, would you?

Why the Montevina Treatment Plant Needs an Upgrade

The Montevina Water Treatment Plant was originally commissioned in 1970, which was four years before the Safe Drinking Water Act was passed in 1974. Since then, water treatment technology has drastically improved and we now know more about water quality and how to best achieve a healthy, safe water supply.

It was necessary to upgrade the plant to meet new regulatory standards and maximize the use of local water resources available to our community.

When the water treatment plant was originally built, it had limited pre-treatment abilities. The facility design and treatment technologies didn’t reflect newer methods that improve the efficiency of the treatment process and allow us to maximize the amount of water sent on to our customers.

For example, the previous design did not allow San Jose Water to treat water during storms, when mountain sources are often at their peak flows. During storms, small natural particles rise and move around, which makes the water murky and less transparent. The measurement of this murkiness is called turbidity and it is strictly regulated under water quality regulations because it’s a proven indicator of filtration efficiency and public health protection.

The plant was unable to treat water during heavy storms because it was unable to consistently remove the increased levels of turbidity in the water.

  • Old Montevina plant capability: 15 NTU in source water
  • New Montevina plant capability during storms: 500 NTU in source water
  • New Montevina plant capability during regular operations: 100 NTU

What Improvements Are Being Made to the Water Treatment Plant?

  1. Add a new step to the treatment process – A new step in the water treatment process has been added to efficiently remove most of the sediment before final filtration, and pump it to a solids handling facility for dewatering and disposal. By adding this step, the remaining water that goes through further treatment is significantly cleaner.
  2. Use of membrane filtration instead of sand filtration – In the past, sand filtration was used to remove unwanted contaminants within one step of the water treatment process. The new Montevina Water Treatment Plant will replace the old sand filtration system with ultra-filtration membranes that are more efficient at removing bacteria, viruses and other contaminants. With this change, the Montevina Water Treatment Plant will be the largest plant in the U.S. using this cutting-edge, proven type of membrane.
  3. Upgrade of the solids handling facility – The new water treatment process will better separate solids so that they may be properly disposed of. The new Montevina Water Treatment Plant is projected to process 90-95% of the water it takes in and turn it into potable drinking water. The industry expects water treatment plants to be at least 90% efficient and the new Montevina plant is expected to be slightly above average due to the benefits derived from the installation of the solids treatment process.


These upgrades help the Montevina Water Treatment Plant meet regulatory standards and ensure our community has access to safe, high quality water for years to come. By making investments in cutting-edge technology, we are better ensuring that the benefits will be longer lasting and more profound.

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