PFAS, short for per- and polyfluoroalkyl substances, are a group of thousands of synthetic chemicals used since the 1940s in products like nonstick cookware, waterproof clothing, firefighting foam, and food packaging. They are often called “forever chemicals” because they do not break down in the environment. Over time, PFAS have seeped into groundwater, rivers, and reservoirs, eventually reaching public and private drinking water wells. When that happens, the question of who pays for the damage and cleanup becomes a legal fight. Understanding the types of liability that apply to contaminated drinking water sources is essential for anyone who owns a well, runs a water utility, or lives near a known contamination site.
The most straightforward liability in PFAS cases is against the manufacturers who created and sold the chemicals. Companies like 3M, DuPont, and others have known for decades that PFAS are toxic and persist in the environment, but they continued to produce them without adequate warnings. Courts have held these manufacturers liable under theories of product liability, negligence, and public nuisance. Product liability focuses on the chemical itself being unreasonably dangerous. Negligence asks whether the company failed to act with reasonable care in testing, labeling, or disposing of the product. Public nuisance claims argue that the contamination interferes with a right common to the public, such as access to clean drinking water. These claims can result in large settlements or verdicts that fund water treatment systems, medical monitoring, and compensation for property value loss.
But manufacturers are not the only potential defendants. Companies that used PFAS in their operations, such as metal platers, paper mills, and airports that trained with firefighting foam, can also be held liable. These entities may have discharged PFAS directly into the ground or into wastewater that later contaminated drinking water sources. Liability here often comes under state and federal environmental laws, such as the Comprehensive Environmental Response, Compensation, and Liability Act, better known as the Superfund law. That law allows the government or private parties to sue “potentially responsible parties” for cleanup costs, regardless of whether the disposal was legal at the time. The standard is strict liability, meaning you do not need to prove the company acted negligently. If your property or your product released PFAS into the environment and that PFAS ended up in someone’s drinking water, you can be forced to pay for remediation.
Water utilities and municipal suppliers also face liability, though of a different kind. A water utility is not usually the one that put PFAS into the ground. But it is responsible for delivering water that meets the Safe Drinking Water Act standards to its customers. If a utility knows or should have known that its source water contains PFAS at levels above health advisory levels, it may be sued by customers for negligence or breach of contract. Some courts have also allowed claims under the public trust doctrine, which says the government must protect essential natural resources for the people. A water utility that fails to test, fails to treat, or fails to inform the public about PFAS contamination can be liable for health problems, lost wages, and even emotional distress caused by the fear of future illness.
Private well owners have a different legal path. They are not covered by municipal water regulations, so they must rely on the polluter being identified and held accountable. In many states, the property owner can sue the polluter for trespass, nuisance, or diminution of property value. Trespass occurs when PFAS physically enter the property without permission. Nuisance occurs when the contamination interferes with the use and enjoyment of the property. These are common law claims, meaning they come from court decisions rather than written statutes. They can be successful, but they require showing that the defendant’s actions directly caused the contamination, which can be difficult when there are multiple sources.
Government entities also have liability exposure. Military bases and airports that used PFAS-laden firefighting foam have contaminated nearby drinking water sources for decades. The federal government can be sued under the Federal Tort Claims Act for negligence, but certain defenses and caps on damages apply. State governments that allowed the use of PFAS or failed to regulate it may also be sued, but sovereign immunity often protects them unless a state law specifically waives that protection.
One of the trickiest parts of drinking water liability is proving that a specific defendant’s PFAS caused a specific health problem. PFAS are linked to cancer, thyroid disease, immune system suppression, and developmental issues. But many people have been exposed to multiple chemicals over their lives. Courts increasingly accept epidemiological evidence, scientific studies of large populations, to show that PFAS exposure is more likely than not responsible for a person’s illness. This shifts the burden to defendants to prove otherwise.
Ultimately, legal liability for contaminated drinking water sources boils down to causation, foreseeability, and responsibility. The person or company that created the pollution, knew it could harm people, and did nothing to stop it is usually the primary target. But water suppliers and landowners also have duties to test, disclose, and treat. The law in this area is still evolving, especially as the federal government moves to set enforceable limits on PFAS in drinking water. As more contamination sites are discovered, the number of lawsuits will only increase.
