SJW staff member testing water

Water Quality 101

We are proud to serve over one million customers with high quality, life-sustaining water along with exceptional customer service. On top of that, we are always committed to supplying water that meets or surpasses all state and federal drinking standards. But what steps do we take to ensure that our water is safe, and how do we determine overall water quality? We take three main factors into account.


Most of our water contains two harmless minerals: calcium and magnesium. These minerals are formed when water comes into contact with limestone, which contains calcium and dolomite, which introduces magnesium. Together, calcium and magnesium give water its “hardness”. You may notice hard water on your showerhead and shower doors. Although you may find it troublesome, hardness does not affect the safety of your water supply. More information about what you can do about hard water in your home can be found on our website.

Because the water in our area contains calcium, you may also notice cloudiness, especially when the water is cold or frozen. This is a natural process and is completely harmless. You may also sometimes notice rusty or reddish water. While this may be alarming, it is often a common result of older pipes in your home. Although rusty water is not a health hazard, you may want to think about replacing your pipes. Letting the water run for a few minutes will also help clear out your pipes and your water.

How is your water supposed to taste? This is a question that always depends on where the water comes from. San Jose Water receives 50% of our water from state or federal water projects through Valley Water. Downtown San Jose receives its water from deep wells, while the communities of Saratoga and Los Gatos get their water supply from our local mountains. Each source of water may taste a bit different. But, we always treat water with chlorine to the minimum required for effective disinfection. If you feel like the taste is objectionable, please call our Customer Service team at (408) 279-7900. Some people might be sensitive to the taste of chlorine so placing a pitcher of water in your fridge to cool it will help the water taste fresher.


There are many steps in determining the overall quality of your water. We are committed to keeping our water 100% safe for our customers for years  to come. Last year, we renovated our Montevina Treatment Plant with state of the art ultrafiltration technology to improve our water treatment process. Read more about how we treat your water and check out a cool video about our renovated plant!


Water Quality Report

You can learn more by reading our Water Quality Report