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EWG's Tap Water Database

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State of American Drinking Water

When most Americans drink a glass of tap water, they're also getting a dose of industrial or agricultural contaminants linked to cancer, brain and nervous system damage, developmental defects, fertility problems or hormone disruption. That's the disturbing truth documented by EWG's Tap Water Database – the most complete source available on the quality of U.S. drinking water, aggregating and analyzing data from almost 50,000 public water utilities nationwide.

The vast majority of the nation's drinking water supplies get a passing grade from federal and state regulatory agencies. However, many of the 250-plus contaminants detected through water sampling and testing are at levels that are perfectly legal under the Safe Drinking Water Act or state regulations, but well above levels authoritative scientific studies have found to pose health risks.

What's more, the Environmental Protection Agency has not added a new contaminant to the list of regulated drinking water pollutants in more than 20 years. This inexcusable failure of the federal government’s responsibility to protect public health means there are no legal limits for the more than 160 unregulated contaminants the tests detected in the nation’s tap water.

Unanswered questions

Utilities must treat their water to meet state and federal standards before piping it into homes, schools and businesses, but water treatment chemicals can themselves produce other potentially harmful contaminants. Utilities must also provide annual water quality reports to their customers, but those reports leave many unanswered questions, such as:

  • How did these contaminants get into drinking water?
  • What's the truly safe level of a contaminant – not just for healthy adults, but for babies and children whose brains and bodies are still developing, pregnant women and their developing fetuses, and people with medical conditions that make them more susceptible to chemicals' effects?
  • Why do regulatory standards focus on keeping treatment costs down instead of protecting public health?
  • What contaminants are in the water that local utilities are not required to treat?
  • How can individuals take steps to ensure that the purity and safety of their water goes beyond what the law requires?

EWG believes Americans have an absolute right to know the full story about the water they drink. We believe that knowledge will lead to improvements in controlling pollution at the source, tougher regulatory standards, and upgrading of treatment plants, delivery pipes and other drinking water infrastructure.

The Tap Water Database lets people enter their zipcodes to see exactly what contaminants were found in their water, at what levels, and what this could mean for their health. It provides information on the most widespread and potentially harmful contaminants and their sources – including agriculture, a leading source of pollution in the U.S. that is largely exempt from federal laws designed to protect drinking water.

Contaminants of concern

EWG collected data from state agencies and the EPA for drinking water tests conducted from 2010 to 2015 by 48,712 water utilities in 50 states. All told, the utilities, which had the opportunity to review the data for accuracy, tested for 500 different contaminants and found 267. Contaminants detected included:

  • 93 linked to an increased risk of cancer. More than 40,000 systems had detections of known or likely carcinogens exceeding established federal or state health guidelines – levels that pose only negligible health risks, but are not legally enforceable.
  • 78 associated with brain and nervous system damage.
  • 63 connected to developmental harm to children or fetuses.
  • 38 that may cause fertility problems.
  • 45 linked to hormonal disruption.

In the summer of 2015, the scandal of extremely high levels of lead in the drinking water of Flint, Mich. – discovered only because a worried mother contacted the EPA after her children got sick – set off national alarm and led to revelations of lead contamination in communities and schools across the country.

There is no safe level of exposure to lead, especially for young children, who can suffer irreversible brain damage from drinking water with any amount of the poison. The data compiled by EWG show that between 2010 and 2015 almost 19,000 public water systems had at least one detection of lead above 3.8 parts per billion, the level at which a formula-fed baby is at risk for elevated blood lead levels.

But the Tap Water Database also reveals nationwide detection of other drinking water contaminants at levels that are legal but scientists and medical experts say are not fully protective of public health. For example:

  • Chromium-6 or hexavalent chromium – an industrial chemical made notorious by the film “Erin Brockovich,” but unregulated under the Safe Drinking Water Act – has been detected in drinking water supplies for more than 250 million Americans in all 50 states, at levels exceeding those California state scientists say pose a negligible risk of cancer for people who drink it daily for a lifetime.
  • Tap water supplies for over 7 million people in 27 states had detections of 1,4-dioxane – an unregulated industrial solvent and an unwanted byproduct in consumer goods such as detergents, shampoos and cosmetics – at levels above those the EPA considers to pose a negligible cancer risk.
  • In 2015, more than 1,800 water systems serving 7 million Americans in 48 states detected nitrates - chemicals from animal waste or agricultural fertilizers - at an average above the level the National Cancer Institute research shows increases the risk of cancer, which is a concentration just half of the government's legal limit for nitrate in drinking water.*

For the levels this database endorses as safe, we relied on the best available science, going far beyond regulations that are too often driven by political compromise with polluters rather than protecting public health. Going forward, EWG will determine and publish truly safe standards not only for toxic chemicals in drinking water, but also for those in food and consumer products. These EWG-endorsed levels are referred to in this database as health guidelines.

Geographic and income inequities

The quality of drinking water can vary greatly depending on not only where it comes from, but where you live, which is often tied to income levels.

Pesticides and toxic byproducts from fertilizer and manure are found by water utilities in many areas of the country, but are often detected in greater numbers and at higher readings by utilities serving rural communities in places where agriculture has a significant footprint.

For example, water tests in Topeka, Kan., found at least four pesticides used on corn fields, including atrazine – the second most-widely used weedkiller in the U.S. – which studies find can turn male frogs into females after exposure to levels of the pesticide commonly found in drinking water sources throughout the Corn Belt.

In Iowa, the Des Moines Water Works battles daily to keep nitrate levels from uncontrolled farm pollution just below the EPA legal limit of 10 parts per million, or ppm, in local drinking water. Based on the findings of the National Cancer Institute, EWG’s health guideline for nitrates is 5 ppm, but the average level found in 2015 by the Des Moines utility was more than 7 ppm.

Among the largest utilities, the East Los Angeles Water District detected the most contaminants of concern overall, with 14 different pollutants in its 2015 water tests above established health guidelines. The district serves 115,000 people in an area whose median household income in 2010, the most recent year for which data is available, was more than 20 percent below the national average.

By contrast, the water system for Merrick, N.Y., serving 117,000 citizens on Long Island, is one of the cleanest in the nation, detecting only one contaminant, chromium-6, above health guidelines in 2015. Merrick’s median household income in 2010 was more than two-and-a-half times the national average.

What should concerned Americans do?

Citizens can take steps to make sure they and their families are drinking the cleanest, safest water possible. The right in-home water filtration system can dramatically reduce the presence of many contaminants utilities detect. EWG’s Water Filter Guide lets users search for the types of filters designed to remove or reduce specific contaminants of concern.

But drinking water contamination is not just a personal concern. It affects everyone in the entire nation. Americans should not take safe drinking water for granted. Instead they must get informed on what comes out of their taps, and the contaminants fouling streams and rivers, and then take action. Ensuring a safe water supply is a fundamental responsibility of government, and we must demand that our public officials at every level step up and fix this broken system.

President Trump has promised to make protecting the nation’s drinking water a top priority of his administration. But he and EPA Administrator Scott Pruitt have taken or proposed a series of alarming actions that would further undermine the government’s ability to make good on that promise, including cutting and eliminating programs and resources for water protection.

Safe drinking water isn’t a privilege, but a right. This database is more than just a helpful resource for individuals and families, but a call to action for everyone who cares about clean water. In the richest country on Earth, every American – rural or urban, affluent or lower-income – should be able to rest assured that the water in their homes, schools and public places is clean and safe to drink.

* Systems have two ways to report nitrate results - as “nitrate” and “nitrate and nitrite." Systems may report both types of nitrate results. EWG's calculation of 7 million people exposed to nitrate above the health guideline is a combination of both types of nitrate results and does not double count systems that reported values for both types of nitrate.