Proposed Chromium 6 MCL

MSWD is proud to serve some of the best-tasting drinking water in the world. The State Water Resources Control Board recently released a Notice of Proposed Rulemaking for hexavalent chromium (Chromium-6), proposing a Maximum Contaminant Level (MCL) of 10 parts per billion (ppb). Following are Questions and Answers related to the proposed rulemaking.

What is hexavalent chromium?
Chromium-6, or hexavalent chromium, is a mineral that occurs naturally throughout the Coachella Valley. Chromium is an odorless and tasteless heavy metal that occurs throughout the environment.

What is changing?

The award-winning water MSWD has proudly served for the last 70 years is not changing. Simply put, the State has proposed changing the way it monitors and regulates Chromium-6.

What is MSWD doing to comply with the new standard?
Our response to Chromium-6 is part of the District’s ongoing Capital Improvement Plan. We have allocated funding during the current fiscal year to study the impact of the proposed 10 ppb MCL and have engaged Corona Environmental Consulting to assist MSWD in reviewing our water quality data and to analyze the applicability of known Chromium-6 treatment options. 

How much time does MSWD have to comply with the new Chromium-6 MCL?
Based on the current information provided by the State, MSWD anticipates we will have 2 years to become compliant after the MLC is adopted. Keep in mind, the state is currently receiving public comments on the proposed MCL, so the date when the MCL will take effect is still unknown. We believe the fastest MSWD would have to place wells in stand-by or provide treatment is about 3 to 4 years.

Should I be concerned about Chromium-6 in my water?
Chromium-6 is being regulated for potential health impacts after decades of consumption, not for immediate health risks. Health risk information can be found on the CalEPA Office of Environmental Health Hazard Assessment website (

How much chromium-6 is in my water?
Levels of Chromium-6 in MSWD' s service area are below the proposed MCL at most of our wells. However, a few wells have shown levels at or above the new standard.

Is tap water safe to drink?
Yes. Your tap water can still be used for drinking, cooking, and all other needs. Chromium-6 is being regulated by the state for potential health impacts after many years of consumption, not for immediate health risks. It is our mission to provide safe, reliable drinking water.

Have I been drinking water polluted with chromium-6?
No. Chromium-6 occurs naturally in local groundwater at levels meeting the state and federal standard for total chromium and is not the result of pollution. Your drinking water meets all the standards in one of the most highly regulated environments in the world.

Where can I find more information on the quality of my water?
More information about the quality of your water can be found in our annual Water Quality Report at We also have printed copies at our office.

How can I remove Chromium-6 from my water?
Residential point-of-use (POU) and point-of-entry (POE) devices can be purchased by individuals to reduce exposure to contaminants in their household water. POU devices (often pitcher filters) are much more common than POE devices for hexavalent chromium treatment. A list of certified residential POU and POE devices capable of treating hexavalent chromium is available on the State Water Board’s website.

Will this affect my water bill?
The District is evaluating several compliance options and their associated impacts to MSWD customers. Our goal is to comply with the state mandate at the lowest possible cost to our customers.

If you have any additional questions about chromium-6 or any other water quality information, please call Mission Springs Water District at 760-329-6448 or visit