Everyone should have clean drinking water. But millions of Americans are exposed to harmful contaminants in their tap water.
Despite decades of federal regulations, much work remains to be done to protect public health. Just because a contaminant is considered “legal” by federal standards doesn’t mean it’sas safe for drinking as it should be.
EWG has craftedhealth-based standards that focus solely on what’s safe for public health in light of the most recent science. In contrast, federal standards must consider cost and feasibility and are rarely updated.For over 20 years, EWG’s no-compromise approach has worked to protect families from exposure to harmful substances in water and to hold polluters accountable.
The Environmental Protection Agency has fallen behind in ensuring safe drinking water for all Americans. EWG steps into the gap by advocating for safe, clean water guided by standards that put public health first.
Gaps in federal regulation
The Safe Drinking Water Act, enacted in 1974 and weakened by amendments in 1996, regulates drinking water supplies. Its intent is to protect the public health of all Americans. But the EPA currently regulates onlyabout 90 contaminants out of the324 substances detected in U.S. tap water.
Further, many of the regulations that the EPA has issued under the law are outdated, with some last updated in the 1990s. Millions of Americans are left vulnerable to unsafe levels of chemicals in their drinking water.
Most community water systems meet the EPA’s legal standards. But these standards do not guarantee safety, as health harms can occur even at those levels. This disparity is particularly problematic when it comes to emerging contaminants, some of which have been linked to serious health issues, such as cancer, brain and nervous system damage, fertility problems and hormone disruption.
The EPA approach to guidelines
Regulating contaminants in drinking water begins with identifying chemicals, heavy metals and microbes that may pose health risks.
The EPA keeps aContaminant Candidate List of substances that may need regulation. Experts review it then determine whether a contaminant poses enough of a public health risk to warrant legal limits. If so, the EPA can set a maximum contaminant level, or MCL, which is the highest allowable concentration of a contaminant in drinking water.
But this process has often been very slow and reactive.
In particular, the agency dragged its feet on regulating the toxic“forever chemicals” known as PFAS, which have contaminated drinking water for hundreds of millions of Americans and are linked to serious health risks. The EPA took over 20 years tofinalize MCLs for six PFAS compounds. To date, these are the only chemicals for which the EPA has set new limits through the process outlined in the 1996 amendments to the Safe Drinking Water Act.
When the EPA finally did set MCLs, it set them at very low levels, making them among themost health-protective drinking water standardsfor PFAS in the world.
But these limits are now under threat. The chemical industry and water utilities have filed lawsuits to weaken or delay these regulations. They argue that the costs of implementation are too high – but this ignores the full health benefits of the limits, including reducing cancer and cardiovascular diseases.
What are maximum contaminant levels?
The process of establishing MCLs is essential but slow. The EPA has only setone new MCL for hazardous chemicals in thelast 25 years.
But even when regulations exist, there are limitations.
In many cases, the EPA doesn’t update the rules to keep up with emerging science or the realities of public health risks. The agency must conduct a cost-benefit analysis before finalizing regulations, and it is much easier to calculate costs than public health benefits. The cost of implementing and complying with these regulations can also pose a significant burden, particularly for smaller water systems. These financial concerns can influence regulatory decisions, at the expense of public health.
What is the Unregulated Contaminant Monitoring Rule?
One key tool the EPA uses to monitor contaminants is theUnregulated Contaminant Monitoring Rule, or UCMR. This program helps the agency identify and track emerging contaminants, which haven’t yet been regulated. The program is crucial for tracking potential dangers,like PFAS, and assessing their presence in drinking water.
The EPA released the most recent data from UCMR 5in November 2024. More PFAS test results were expected in February 2025. It was anticipated they would provide critical information on 29 PFAS compounds in tap water nationwide. But there is no clear timeline when the EPA will disclose the information, despite plans for tests throughout the year.
The delay hinders the ability of the EPA and public health officials to respond effectively to emerging contaminants and may leave millions of Americans at risk.
As of now, more than143 million Americans are exposed to toxic PFAS chemicals in their drinking water. This widespread contamination underscores the critical importance of the EPA’s health-protective 2024 MCLs.
The UCMR 5 data can help policymakers identify the extent of the PFAS contamination problem. But the delay in its release further shows how the regulatory process often fails to keep pace with the threat of pollution that increasingly imperils U.S. public health.
Health risks of water contaminants
Drinking water contaminants have been linked to a variety of health issues, including cancer, reproductive problems, brain damage and hormone disruption. But most studies focus on the effects of individual contaminants, leaving a major gap in understanding how multiple contaminants might interact in the human body.
In a 2019 study, EWG found that exposure to a mixture of 22 common toxic chemicals in U.S. tap water could result in over an estimated100,000 additional cancer cases.
This finding highlights a critical flaw in the EPA’s current regulatory approach: The agency assesses contaminants and the costs and benefits of reducing levels one at a time – but tap water rarely contains just one chemical.
The EPA has not adequately addressed the combined effects of multiple pollutants, which has left a significant gap in public health protection.
And even when regulations are in place, enforcement is often weak.
The EPA and state agencies struggle to monitor compliance with limited resources. They also sometimes grant water systems with long-term “temporary” waivers for violations, further undermining public health protection.
Drinking water standards passed by states
While the federal government sets baseline standards, many states have stepped in to implement their own, often stricter, regulations, particularly for emerging contaminants like PFAS. And many states have taken the lead in setting stronger limits on drinking water contaminants such as1,4-dioxane andhexavalent chromium in drinking water, going beyond federal standards.
For instance,11 states have already set limits for certain PFAS compounds in public water systems, and other states have adopted health advisories or notification levels. These state-specific regulations are critical in addressing local water quality issues, especially when federal standards fail to protect public health.
In California,Assembly Bill 794 seeks to ensure strong state drinking water standards that will protect residents from harmful PFAS contamination. The bill would require the state water board to implement emergency regulations that match or exceed current federal standards, while also providing the state the flexibility to conduct its own analysis and implement stronger protections, if needed.
Such state-level efforts highlight the importance of addressing local needs and challenges, often where federal regulations fall short.
The Bipartisan Infrastructure Law
TheBipartisan Infrastructure Law, enacted in 2021, provides a critical boost to water infrastructure by allocating $21 billion for states and communities to modernize their drinking water systems. This funding focuses on addressing contaminants like PFAS, replacing lead pipes and upgrading aging infrastructure. But the Trump administration is trying to roll back this funding. It is uncertain whether the funds are still being disbursed.
Technologies like activated carbon and reverse osmosis systems will help improve water quality by removing harmful substances, ensuring all communities benefit equally, with a significant impact in underserved communities where access to clean water has historically been limited.
This investment in water infrastructure is essential for providing safer drinking water for millions of Americans. It also supports the EPA’s efforts to regulate and monitor contaminants, ensuring that states have the resources needed to meet updated federal standards.
Recent Supreme Court ruling
A recent 5-4 ruling by the U.S. Supreme Court in City and County of San Francisco v. EPA now limits the EPA and state’s authority to regulate stormwater pollution. The decision could make it harder to regulate or monitor these pollutants at the source, potentially increasing contamination risks.
This decision removes a key tool used to enforce water quality standards for pollutants beyond treatment facilities, including emerging contaminants like PFAS. While environmental groups have criticized the ruling for weakening the Clean Water Act, industry groups argue it clarifies permit requirements.
This decision may lead to confusion in future water quality permits and delays in amending permits or issuing new permits, making enforcement more difficult and delaying progress.
What you can do
If you’re concerned about contaminants in your tap water, afiltration system can be a practical solution.
Filtration options like activated carbon and reverse osmosis are effective at reducing a wide range of harmful substances.
EWG has tested severalhome water filter pitchers to help consumers find the best options for their needs.
You can also use EWG’sTap Water Database to learn more about the contaminants in your local water supply. This database helps you understand what’s in your tap water and empowers you to make informed decisions.
We are still a long way from ensuring safe drinking water for all. It’s concerning that this administration may weaken drinking water protections for PFAS, including by failing to hold polluters accountable that discharge harmful industrial chemicals into water sources.
One of the best ways to ensure cleaner water is to hold elected officials’ feet to the fire – whether at the local, state or federal level. Byasking the right questionsand demanding action, people can push for stronger regulations on harmful contaminants in drinking water.