California’s 1,4-Dioxane Notification Level Explained

1,4-dioxane is a water contaminant that has been widely detected in groundwater and surface water due to decades of use in industrial and consumer products. The State of California is one of several states that have taken steps to reduce the concentration of this chemical in drinking water supplies. While California is in the process of setting an enforceable maximum contaminant level (MCL) for 1,4-dioxane, the state has already established notification and response levels to guide public water providers when detections occur.

Traditional water treatment methods are ineffective for 1,4-dioxane, so water providers seeking to remove it from drinking water must incur additional costs to build, operate, and maintain new treatment plants. Municipalities and utilities are merely passive receivers of 1,4-dioxane, as they do not produce the chemical. As such, they shouldn’t have to bear the financial burden for the cleanup.​ However, because California water providers are subject to notification requirements when detections exceed certain concentrations and the state is in the process of developing an MCL, they may end up saddled with cleanup costs if they decide to treat their water to remove 1,4-dioxane. In these cases, water systems often have no choice but to pass the costs along to ratepayers. As a result, some leaders of water systems affected by 1,4-dioxane are seeking alternative revenue options to protect utilities and ratepayers from this financial impact.

In this article, we will explain the State of California's notification and response levels for 1,4-dioxane, along with the recommendations and requirements for water sources with exceedances. Then, we will review available funding to protect utilities and ratepayers from high treatment costs. Finally, we will evaluate the benefits of incorporating litigation into funding strategies to support 1,4-dioxane mitigation and other important initiatives.

What is 1,4-Dioxane?

1,4-dioxane is a colorless liquid primarily used as a stabilizer in various industrial applications, such as solvents, greases, waxes, and detergents. It can also form as a byproduct during the manufacturing process of some personal care products. The chemical enters the environment when these products are used or disposed of, including through treated wastewater streams, as traditional wastewater treatment technology does not remove 1,4-dioxane. According to the U.S. EPA, 1,4-dioxane presents a public health risk when found in elevated concentrations in drinking water. Research has shown exposure to the contaminant can increase the risk of cancer and harm the liver and nasal tissue, leading some states to develop guidelines and regulations to protect public health.

How is 1,4-Dioxane Regulated in California Drinking Water?

The California State Water Resources Control Board Division of Drinking Water (DDW) has established notification and response levels for 1,4-dioxane in drinking water. These levels impose certain recommendations and actions on water providers when exceedances are detected, but they do not require treatment to remove contaminants as an MCL would. In the past, the State of California has continued the regulatory process for some contaminants after setting notification and response levels, eventually imposing MCLs. While it remains to be seen whether this will ultimately occur for 1,4-dioxane, the state has already taken some steps toward this goal.

Understanding 1,4-Dioxane Notification Levels in California

California's 1,4-dioxane drinking water notification level is 1 microgram per liter (μg/L). This level was reduced from the previous notification level of 3 µg/L in 2010, based on an updated risk evaluation from the U.S. Environmental Protection Agency (EPA). In fact, EPA's recommended, non-enforceable drinking water goal of 0.35 µg/L is even lower than California's notification level of 1 µg/L, but California took the limitations of available testing and treatment methods into account in setting its limit.

DDW currently requires drinking water systems that detect 1,4-dioxane in concentrations above 1 µg/L to notify the governing body of the local agency in which residents consume the water. This may include a city council or county board of supervisors. In addition to this required notification, DDW recommends that utilities inform customers and consumers of the contaminant detection if they are served water exceeding the notification level. Impacted water providers may consider including information about health risks in their annual Consumer Confidence Reports or other mailings and publications available to the general public.

What is California's 1,4-Dioxane Response Level?

The California DDW's 1,4-dioxane response level 35 µg/L. Water sources with detections above this level are recommended to be removed from service until the concentration can be reduced to below 35 µg/L. While this is a recommendation, not an enforceable requirement, DDW suggests water providers that continue serving water that exceeds response levels take the following precautions:

• Notify the local governing body of the response level exceedance.

• Notify customers and water consumers, including populations such as renters, workers, and others who may not directly receive such updates through Consumer Confidence Reports or water bills.

• Issue a press release to the local media.

• Continue monitoring 1,4-dioxane concentrations on a monthly basis until contaminants can be reduced to below the response level.

Although the steps listed above are recommendations and are not required by statute, California water providers should be aware that DDW has the authority to provide these public notifications in the event that a water system does not do so. The risk of public scrutiny that could result from such alerts may spur some utilities to implement mitigation strategies, ensuring that 1,4-dioxane levels remain below California's notification and response levels.

Recommended Next Steps for Water Providers with 1,4-Dioxane Detections

While some municipalities and water utilities may be able to remove contaminated water sources from service while continuing to meet customer demand, many will require advanced treatment solutions to remove 1,4-dioxane from drinking water. While effective treatment methods are commercially available, they can cost tens of millions of dollars to implement, creating a significant financial burden for water providers.

Are California Water Utilities Required to Test for 1,4-Dioxane?

Because California has not yet set an enforceable MCL for 1,4-dioxane, water utilities are generally not required to conduct regular water quality testing for this contaminant. However, the State Water Resources Control Board may direct some water providers to sample for it in specific situations. In addition, some water systems may choose to proactively test for 1,4-dioxane to protect public health if contamination is suspected.

Should Municipalities Conduct Water Quality Testing for 1,4-Dioxane? 

Most public water providers in the United States were required to test for 1,4-dioxane between 2013 and 2015 under UCMR 3, so systems concerned about whether 1,4-dioxane has ever been detected in their water supplies can consult past records to see if results were recorded at that time.

Systems that were not required to perform testing under UCMR 3, or that suspect that contaminant levels may have increased since then, should consult their legal counsel to determine whether voluntary testing is warranted. Each water system will need to evaluate its 1,4-dioxane contamination risk factors along with its routine testing budget and timeline to make the best decision regarding 1,4-dioxane testing.

Future Regulatory Trends for 1,4-Dioxane

The growing evidence of 1,4-dioxane's risks to public health has prompted several states to respond by developing regulations. New York was the first state to set a legally enforceable MCL for the contaminant, and New Jersey, Illinois, and Virginia are in the process of developing MCLs. California may follow suit in the near future.

As mentioned above, notification and response levels are sometimes used as a starting point for the development of MCLs in the State of California. Meanwhile, the U.S. EPA also published an updated risk evaluation for 1,4-dioxane, stating that the chemical presents an unreasonable risk to human health. While this risk evaluation does not impose any federal regulatory requirements on water providers, it may be an indicator of future development of EPA guidelines.

Is California Developing a 1,4-Dioxane MCL?

The California State Water Resources Control Board began the process of developing an MCL for 1,4-dioxane in 2019 by requesting that the Office of Environmental Heath Hazard Assessment (OEHHA) establish a public health goal (PHG) for the contaminant. This is the first step towards setting an enforceable drinking water standard, as a potential MCL must be set as close to the PHG as is feasible using the testing and treatment methods widely available to water providers. California water utilities can prepare for impending regulations by planning for 1,4-dioxane mitigation now.

How Can Water Providers Recover 1,4-Dioxane Treatment Costs?

As evolving regulations lead to increased costs, water providers are looking for innovative funding strategies to support water treatment and other 1,4-dioxane mitigation projects. State and federal funding initiatives may provide opportunities for municipalities, counties, and other water providers to secure grants or additional financial support. However, these funds often do not cover the full cost of implementing new treatment technologies, leaving water providers to find other funding solutions to close the gap.

Over the years, many water providers have incorporated litigation as an additional revenue stream to fill funding gaps for contamination clean-up. For example, many water systems in California have recovered funds to clean-up 1,2,3-TCP contamination in their water sources. Over the past 5 years alone, SL Environmental Law Group obtained nearly $160 million in settlements for utilities, businesses, and schools impacted by this contaminant, including cases where TCP levels were below regulatory standards.

In another recent example, local governments and utilities nationwide were able to hold PFAS manufacturers 3M, DuPont, TYCO, and BASF accountable for the impact of PFAS contamination.  In fact, the manufacturers recently agreed to pay a combined amount of nearly $15 billion in settlements to eligible public water providers affected by PFAS contamination.  

Water utilities affected by 1,4-dioxane contamination can utilize similar legal strategies to seek to protect their communities from the burden of cleanup costs.

Making 1,4-Dioxane Manufacturers Pay for California Water Contamination

With California state notification and response levels already in effect, and MCLs potentially on the horizon, water providers may face significant treatment and monitoring costs. Systems impacted by 1,4-dioxane contamination will need innovative funding sources to cover these costs. By exploring litigation as a cost recovery strategy, systems can seek to minimize the financial burden of contamination on their utilities and ratepayers.​

Working with a firm that specializes in environmental law and contamination cost recovery can help municipalities and utilities navigate the legal process and ensure that they are pursuing the best options for their unique situation. These firms have experience in managing similar cases and understand their complexities.

If you have questions about your municipality, county, or water system's options for 1,4-dioxane treatment cost recovery, schedule a free consultation with our legal team.