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Before the Environmental Protection Agency (EPA) was established in 1970, it was estimated that as much as 40% of the nations’ public water systems failed to meet basic health requirements. In the following decades, the safety of public water systems in the US made major advancements.

Today, more than 90% of Americans have access to drinking water through public water systems, which are regulated at the state and local level according to federal guidelines. As of 2021, about 1% of all public water systems are serious violators, meaning they are accountable for the most severe and persistent violations nationwide.

The enduring number of public water system violations over the last decade indicates that the US still has underlying problems with its drinking water. This stems, in part, from a high rate of monitoring and reporting violations which fail to adequately test water supplies.

Some cities across the country have persistent water quality issues as a result of lead service pipelines, which threaten to contaminate local drinking water.

There are still six to 10 million lead service lines in cities and towns across the country, many of which are in communities of color and low-income neighborhoods. Recent efforts to improve national water infrastructure indicate a potential reduction to systemic water quality issues.

Where does drinking water come from?

As of 2021, there are more than 150,000 public water systems in the US. Approximately one third of these systems serve communities year-round, ranging from neighborhoods in small towns, to whole cities.[1] Two-thirds of water systems serve other properties, such as hospitals, jails, and schools.

Large cities with populations of 100,000 people or greater typically receive their own dedicated public water system. Suburban and rural communities can receive their drinking water through multiple systems or a single regional system, depending on their location.

There are roughly 27,000 public water systems serving populations of less than 500 people year-round, covering approximately 4.46 million people across US states and territories, or 1.3% of the total population. Only a small subset of these systems reach a majority of the population on a yearly basis.

The U.S. Geological Survey (USGS) estimates that more than 43 million Americans, or roughly 15% of the population, rely on domestic wells as a source of drinking water. These private wells are not regulated by the EPA or, in most cases, state laws, meaning homeowners are responsible for maintenance.[2]

How does the government ensure drinking water is safe?

Public water systems must meet standards set by the Safe Drinking Water Act (SDWA) and contain minimal levels of contaminants which may impact public health.[3] The EPA requires public water systems to test for more than 90 contaminants, along with separate lists of secondary contaminants and unregulated contaminants up for future review.

These contaminants range from chemicals such as lead and arsenic, which have dangerous long-term health effects at any level, to disinfectants used by public health officials to clean and test drinking water for other contaminants.

In recent years, the EPA has added more chemicals used in industrial production to its regulatory list, such as per- and polyfluoroalkyl substances (PFAS), better known as “forever chemicals”. The Centers for Disease Control and Prevention has found that most people in the U.S. have been exposed to PFAS, likely from consuming contaminated water or food.

Additionally, public water systems serving communities year-round are required to release Consumer Confidence Reports. These annual drinking water quality reports provide Americans with information about where their water comes from, the status of drinking water quality, potential health impacts, and an account of the system’s actions to restore safe drinking water when issues occur.

However, many systems fail to meet EPA standards. These violations can result from failures to notify the public about problems with drinking water, monitoring and reporting violations, or health-based violations in which contaminants found in drinking water have the potential to harm the public.

What were the most common types of water quality violations?

In 2021, there were 153,501 total water quality violations across all US states and territories. More than 63% of the violations were due to monitoring and reporting issues. About 28% were public notification violations. And 7.4% were health-based violations.

Roughly one-fifth of reported health-based violations were identified as acute violations, meaning they had the potential to produce immediate illness.

The high proportion of monitoring, reporting, and public notification violations indicates that tens of thousands of public water systems fail to test and report potential health violations to the EPA and the public, meaning that potential health-based violations may be underestimated.

Since 2012, an average of 23% of public water systems serving communities year-round receive a monitoring and reporting violation in a typical year, meaning a water system failed to adequately test and report on potential contaminants in drinking water.

While total violations in 2021 are down from the 10-year average, the frequency of drinking water violations does not appear to be decreasing over time.

Which public water systems reported health violations?

In the last decade, 305 public waters systems serving 100,000 of more year-round had at least one water quality violation. Of these, 122 systems had at least one health-based water quality violation. More than half of these systems received an acute health-based violation, meaning the population they served was exposed to a contaminant that could cause illness.

The three cities that received the most drinking water violations during this period were all located in Puerto Rico.

The Metropolitano water system, which serves the capital of San Juan, had the highest number of water quality violations over the last decade at 256. This is followed by the Ponce Urbano system at 180 violations, and then the Aguadilla system at 126.

The Metropolitano water system also had the highest number of total health-based violations over the last decade at 85, followed by the Aguadilla system at 62, and then Midland, Texas, at 50.

The Metropolitano water system received 36 acute health-based violations, the highest in the nation by a wide margin.

Each system has its own unique water quality issues. Many public water systems in Puerto Rico suffer from contaminants mixed into drinking water following tropical storms and hurricanes. This had led to the disproportionate number of health-based violations in the territory. Many other US cities, such as Shreveport, Louisiana, have had high rates of sediment in the water caused by a combination of natural factors such as runoff, or human-induced factors such as erosion and untreated wastewater discharges.

Which states have the highest rate of water quality violations?

Between 2012 to 2021, American Samoa had the highest rate of violations per public water system at 133.2, followed by West Virginia at 65.3, and then Puerto Rico at 42.7. Hawaii had the lowest number of violations per public water system at 2.7, followed by Minnesota at 2.8, and then South Carolina at 3.2. The average number of violations per public water system between 2012 and 2021 was 15.2.

In terms of total health-based violations by state, Puerto Rico had the highest rate of violations per public water systems at 7.5, followed by New Mexico at 6.3 and then Oklahoma at 5.2. Michigan had the lowest rate at 0.3, followed by Washington and New York at 0.4. The average number of health-based violations per public water system between 2012 and 2021 was 1.7.

Due to the high proportion of monitoring and reporting water quality violations, the number of health-based violations may be underreported.

As of 2021, approximately 1,500, or 1% of all public water systems, have been identified as serious violators, meaning they are accountable for the most severe and persistent violations nationwide. This total has dropped from 4,400 since 2011.

What are some of the biggest sources for drinking water violations?

The installation of lead services lines between the late 1800s and the 1980s created a longstanding threat to water quality in the US. Lead pipes can corrode if water with high acidity or low mineral content is flowing through them.

But poor recordkeeping makes it difficult to know how many miles of lead service lines still exist in the US.

The EPA has set the contaminant level goal for lead in drinking water at zero since any exposure to the toxic metal can be harmful.

However, it isn’t until more than 10 percent of tap water samples exceed 15 parts per billion that official action is required. This means that many water systems containing trace amounts of lead below the actionable level go unchecked, despite the potential long-term health impacts.

Cities such as Flint, Michigan, and Jackson, Mississippi, have had long-standing issues with lead in drinking water over the last decade, many of which received violations that took years to investigate and resolve. These issues can often show up as a single violation of federal drinking water rules despite the problem continuing for years.

What is the government doing to address drinking water safety issues?

According to the EPA’s Sixth Drinking Water Infrastructure Needs Survey and Assessment submitted to Congress in January of 2015, the agency requires $472.6 billion to maintain and improve the nation’s drinking water infrastructure over the next 20 years. This is nearly double the amount of CPI-adjusted dollars needed to maintain the nation’s water infrastructure between 1995 and 2015.

While information on the location of lead service pipelines is still difficult to compile, a revision to the Lead and Copper Rule passed in December 2021 requires water systems to collect inventory of their pipelines and make the information available to the public. Data from this revision may make it easier for state and local governments to determine how many lead service pipelines need to be replaced and which areas of most in need of service.

Additionally, the Biden administration delivered more than $35 billion through the Bipartisan Infrastructure Law to improve the nation’s drinking water infrastructure. This includes a $15 billion allocation to replacing lead service lines.

The EPA establishes legally enforceable standards for water quality violations to ensure that public water systems stay in compliance with the SDWA. However, unreliable enforcement records make it difficult to assess the success rate of enforcement measures against noncompliant systems.

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EPA/State Drinking Water Dashboard

These public water systems are defined as community water-systems, which serve a set population of people (at least 15) year-round. To learn about other public water system types, visit the EPA’s information page.


Certain households have access to both a public water system and a private well, meaning there is some overlap between these groups.


The SDWA does not regulate public or private water sources which serve less than 25 people year-round.