Don’t Let That Viral Drinking Water Database Scare You

The Environmental Working Group (EWG), an environmentally focused nonprofit, released a new database on Thursday that lets any US resident check what kinds of contaminants are present in their drinking water. The tool aggregates and analyzes publicly available data from nearly 50,000 public water systems across the country. Using the database is an easy way to learn more about what's in your water, and it was quickly picked up by the media. But the way in which the EWG presents its data could cause unnecessary fear.

When I searched for my own Brooklyn zip code, 11237, the database told me that six "cancer-causing" pollutants were in my water at levels above "health guidelines." When I dug deeper into what that actually means and consulted an independent expert, I found that in some cases, the EWG cherrypicks its benchmarks for contaminants from the lowest recommendation available. Instead of informing people about their water, it may leave them needlessly worried. Search for just about any zip code, and users are shown a handful of scary-sounding chemicals, as well as the word "cancer."

But is all the drinking water in the United States causing cancer? Of course it's not that simple. In the US, the federal Environmental Protection Agency (EPA) sets maximum contaminant levels (MCLs) as part of the Safe Drinking Water Act. Because it found these lacking, the EWG based its analysis partially on its own standards.

"When official guidelines are not available or are insufficient to protect public health, we developed our own health benchmarks using publicly available scientific research," reads EWG's data sources and methodology page.

Similarly, on its its "EWG Standards" page, the organization notes the standards were devised using "the best and latest scientific evidence," but does not link to or mention any specific scientific studies it used. On the methodology page, EWG also notes that it relied on EPA standards, California public health goals, and an assessment from the Minnesota Department of Health.

If you're particularly motivated, you can find out which of the standards your water is violating by clicking the plus sign next to each chemical. For example, my water utility reported an average of 30.9 parts per billion (ppb) of chloroform—a chemical used to disinfect water that has been associated with certain types of cancer—in my drinking water in 2015. The EWG's "health standard" is 1 ppb, which makes it seem like my water is more than 30 times too polluted with chloroform.

The EWG explains that this 1 ppb standard "was defined by the California Office of Environmental Health Hazard Assessment." The EPA's maximum containment level goal (MCLG) for chloroform, meanwhile, is 70 ppb. The state of California did not list chloroform specifically as part of its public health goals, but its website states that 20 ppb is the oral "no significant risk level" under Proposition 65, or the the Safe Drinking Water and Toxic Enforcement Act enacted in 1986. Minnesota also set its guidance value at 20 ppb. So where did EWG get 1 ppb?

A spokesperson from the EWG said in an email that it got the figure from a 2010 draft California Office of Environmental Health Hazard assessment, which indicated 1 ppb of chloroform is low enough for a "one-in-a-million" lifetime risk of cancer. In other words, there is some basis for choosing a number so low, but EWG cherry-picked the lowest health guideline it could find even though the document was never finalized.

"Some people look at this and say you're causing alarm or scaring people," Bill Walker, the EWG's vice president and managing editor told me over the phone. "Well we think people are smart enough to take in information and act on it intelligently."

I asked Ashok Gadgil, a senior faculty scientist at the Lawrence Berkeley National Laboratory and a professor of civil and environmental engineering at the University of California, Berkeley to independently review screenshots from the database. He was alarmed at how the EWG presented the data.

"I am glad that you too are cautious about this," he told me in an email. He said that contaminants in water cause harm, and higher concentrations predictably cause more harm, but that fact alone is not the entire story.

"It is not a all-or-nothing matter. i.e., it is incorrect to think that 10 percent below the MCL [the EPA's maximum contaminant levels] all is well, but 10 percent above the MCL causes catastrophic harm," he explained. The EWG's database flags "all concentrations above the MCL as equally bad, and this will either cause panic among the already-worried…or it will be like crying wolf, and [the] public won't eventually care anymore since so many contaminants will be shown above the MCL with no noticeable ill effect on anyone," he went on.

When I spoke to Walker from the EWG, he explained that "legal limits are often the result of compromises" made by lawmakers. "Regulators take those numbers developed by the scientists and they negotiate with the water suppliers and in many cases those responsible for the pollution," Walker said.

Legal limits do represent compromise among lawmakers and water utilities. Under the Safe Drinking Water Act, states conduct a cost-benefit analysis when deciding the limits for water contaminants.

An EPA spokesperson provided the following statement when I asked for comment about the database: "America's drinking water remains among the safest in the world and protecting drinking water is EPA's top priority. We take our commitment to protecting public health seriously and when issues arise, we work closely with states, local governments, and water suppliers to review and address, as appropriate."

The reason the EWG painstakingly created the database in the first place is in part because the EPA's own resources are difficult to navigate and extract meaningful information from.

The EWG is also trying to address very real gaps in the government's oversight and communication about the nation's water sources. For example, the EPA also doesn't yet impose requirements on many contaminants, of which we don't know the long term effects. It's helpful that the EWG lists many of them. An analysis conducted by Reuters in 2016 also showed that almost 3,000 areas across the US were contaminated with dangerous levels of lead. There's little doubt that America's water systems are not always safe.

The EWG recommends that you install a water filter to remove contaminants, which is not necessarily a bad idea. But the organization receives a kickback through Amazon's affiliate program if you purchase a filter through its website. The more people that buy water filters, the more money EWG stands to make (VICE participates in a similar program). An EWG spokesperson said that the organization earns very little from the affiliate program.

If you type in your own zip code into EWG's database and find that your water is full of cancer-causing contaminants, don't panic. Your water is likely safe under federal guidelines.

After watching water crises like the one in Flint, Michigan, I have no doubt that the US doesn't always protect the water we rely on. However, fear-mongering is not the way to make meaningful change.