Hexavalent Chromium

The State of California Has Adopted a More Stringent Hexavalent Chromium Standard

This is not an emergency. You do not need to take any action or seek an alternative water supply. There has been no change to the levels of chromium that have been present in the water supply over the years.

What is Chromium?

  • Chromium is a transition metal and is the 24th element of the periodic table.
  • Chromium is found in rocks, vegetation, animals, soil, and volcanic dust.
  • While there are several states of chromium, chromium-3 and chromium-6 are the most prevalent.
  • Chromium-3, also known as trivalent chromium, is an essential human dietary element found in vegetables, fruits, meats, and other things.
  • Chromium-6, also known as hexavalent chromium, is a metallic element that is both naturally occurring from mineral deposits and a byproduct of industrial processes.

What Are the Regulations Around Hexavalent Chromium?

  • On October 1, 2024, the State of California implemented a new maximum contaminant level (MCL) for hexavalent chromium at 10 parts per billion (ppb).
    • The State's previous hexavalent chromium MCL was 50 ppb.
    • 10 ppb is equal to approximately 10 drops in an Olympic-sized pool.
  • California is the first and only state to set a drinking water standard for naturally occurring chromium-6. See the table below for a comparison of the federal and California chromium standards:
The image lists chromium standards for total, trivalent, and hexavalent chromium levels in U.S. Federal and California regulations.

 

What Should I Do?

  • You do not need to use an alternative water supply (e.g., bottled water). You may continue to drink and use the water.
  • The State of California claims that some people who drink water containing hexavalent chromium in excess of the MCL over many years may have an increased risk of getting cancer.
    • If you have other health issues concerning the consumption of this water, you may wish to consult your doctor.

What is HVLCSD Doing to Comply with This New Regulation?

  • A water system of our size is not considered in violation of the Hexavalent Chromium MCL until after October 1, 2027.
  • On December 18, 2025, we completed a Hexavalent Chromium Compliance Plan that is being reviewed by the State Water Resources Control Board.
  • We are conducting a compliance study to evaluate the technical, operational, and financial feasibility of multiple treatment and blending strategies. This may also include performing field and pilot tests to identify the best solution.

 

Additional Resources

For a copy of the notices that were distributed in December of 2025, please use the following link:

Hexavalent Chromium Public Notice (Dec 19, 2025)

 

For a copy of our Compliance Plan, please use the following link:

Hexavalent Chromium Compliance Plan (Dec 18, 2025)

 

Below are the sources used to compile this information: