Drinking Water Database Reveals the Dirtiest — and Cleanest — Supplies in the US

The Environmental Working Group compiled testing data for nearly 50,000 localities — and the results vary drastically across the country.

How safe is it for you to drink the water that flows from the tap at home or from the water fountain at work or school?

The short answer is: It depends on where you live, according to a new tap water quality database released today by the Environmental Working Group. But if you live in East Los Angeles, you should definitely buy a water filter.

Test results found that the water in East LA has 14 different pollutants exceeding recommended levels, more than any area served by a large utility in the country, according to the database.

By contrast, the water system for Merrick, NY, a Long Island town a few miles east of Brooklyn, is one of the cleanest in the country. Only one contaminant was detected that exceeded recommendations in 2015, EWG said.

“The quality varies drastically throughout the country,” said EWG’s Nneka Leiba, the leader of the tap water project and director of EWG’s Healthy Living Science Program. “It depends on where you live.”

Overall, Leiba said that the database reveals “shocking” amounts of chemicals in the nation’s water supply.

RELATED: Solar Purification Could Provide Clean Water in Rural India

EWG’s new database allows a user to punch in their zip code and check the level of different types of pollutants in their area, covering 48,712 water utilities in 50 states.

The database highlights chemicals like nitrates, which come from agricultural waste or fertilizer and are linked to increased risk of cancer, as well as 1,4-dioxane, an unregulated industrial solvent considered by the US Environmental Protection Agency to be a “likely human carcinogen.

EWG found that US tap water is contaminated by 256 different chemicals with dozens at levels that health specialists say could increase certain health risks. The database indicates 40,000 water systems, or 81 percent of those covered by the study, contained chemicals linked to cancer.

Meanwhile, 19,000 water systems detected lead levels that could be harmful to infants, according to EWG.

That finding follows an investigation by the news agency Reuters in late 2016 that found 3,000 areas with poisoning rates higher than in Flint, Michigan. Many of those areas, reporters found, were receiving little attention from authorities.

RELATED: Water Could Become Unaffordable for a Third of American Households

EWG’s database includes water quality tests conducted nationwide by utilities from 2010 to 2015, encompassing nearly 30 million test results for 502 contaminants.

There are over 151,000 public water systems in the United States, according to the EPA, although that large number includes systems as small as ones serving only 25 people.

Its important to note, however, EWG isn’t claiming that the contaminates exceed legal limits, rather they are raising awareness about the presence of any potentially harmful compounds. In most places, chemical thresholds remain in compliance with regulations.

“Most Americans just hear that their water meets legal standards. But the legal standards are a compromise between health and a political or economic interest,” said Leiba. “Legal doesn’t mean safe.”

Asked for comment about the water in East LA, a spokesperson for the California Water Service said the agency is in compliance with regulatory standards.

“California Water Service is committed to meeting all of the federal and state water quality standards,” said Yvonne Kingman, corporate communications manager for the company, which provides water to 115,000 people in East LA. “Our East Los Angeles customers can rest assured that their water meets all of these standards.”

Kingman added that health guidelines more stringent than what the law allows “are set without regard to cost or available detection and treatment technologies.”