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Is Tap Water Safe to Drink?

Updated: Mar 1

A Metaphor for Income Inequality


Editor’s Note: Thanks to the recommendations of Critica advisor David Menckes, this version, originally posted in January, has been revised.


The question “is my tap water safe to drink?” seems simple enough. We all have at least some basic idea that the water that comes through our faucets is purified somewhere, somehow. People have been drinking tap water in the United States for almost 200 years and many of us don’t think twice about it. Certainly, we are fortunate in this country not to have to worry about water-borne epidemics like typhoid and cholera that still plague many parts of the world.


        If we start reading online articles about drinking water safety, we see that a lot of them start with the refrain “the drinking water in the US is generally safe, but…” We also encounter terrifying articles that claim our drinking water is laced with toxic, cancer-causing, and immune and hormone system disrupting chemicals. Perhaps this is one of the reasons that bottled water is a multi-billion dollar a year industry.

Sometimes, problems do emerge with drinking water, as we have of course seen in Flint, MI and Newark, NJ. But even when real concerns emerge, they often breed fake claims in their aftermath. How do we put the fortunately fairly limited real problems with drinking water in context?

Is our publicly provided tap water safe to drink? (source: Shutterstock)

Where Our Drinking Water Comes From


         Most municipal water comes from lakes, rivers, reservoirs, and groundwater. That water is sent to water treatment plants where it undergoes a variety of filtration and chemical treatments and then is pumped through water mains to service pipes that connect the mains to buildings. The federal Environmental Protection Agency (EPA) sets standards for community water supply systems under the jurisdiction of the Federal Safe Drinking Water Act of 1974; states and localities often have their own, stricter standards for levels of various potentially harmful substances that can be found in drinking water.


         There are over 150,000 drinking water supply systems in the US. The consensus is that public drinking water in the US is among the safest in the world. Yet no less prestigious a source than Science magazine published a story in 2018 with the headline “Millions of Americans drink potentially unsafe tap water. How does your county stack up? Typical of such articles, the story begins by quoting a University of California water economist, Maura Allaire, as stating that the U.S. has really safe water” and then goes on to detail a seemingly frightening number of violations of EPA regulations, leading to higher levels of contaminants in some community water supplies than allowed. And some watchdog organizations, like the Environmental Working Group (EWG), contend that those EPA standards are too lax in the first place. This statement by Goop, Gwyneth Paltrow’s organization, is characteristic of what we can find throughout the internet on the subject of water:

The US has some of the cleanest drinking water in the world. Yet our tap water supply still contains hundreds of contaminants linked to cancer, brain and nervous system damage, endocrine disruption, and many other health effects. Most Americans’ water meets the federal government’s legal requirements. But there is often a big gap between what’s legal and what’s safe.


         So do we have very safe drinking water or dangerously contaminated water? Our review of this topic leads us to the following provisional conclusion: people who live in affluent communities have very safe drinking water, but people who live in poor communities often do not. Thus, in some senses water quality in the US is a metaphor for the country’s well-described and worsening state of income, racial, and class-based inequality.


Claims of Toxic Contaminants Abound


The list of toxic contaminants said to be routinely found in drinking water includes fluoride, chromium, radium, nitrates, PFAS, chlorine, and lead. We will return to the lead problem later in this commentary. Some of these “contaminants” are actually deliberately added to drinking water for specific health-related purposes. Fluoride has been added for decades because of the well-documented finding that it reduces dental decay. Nevertheless, the non-profit organization Fluoride Action Network insists that consuming it can cause cancer and a bevy of other dreaded diseases and also reduces I.Q. in children. Most recently, in a draft report by the National Toxicology Program concludes that fluoride is “presumed to be a cognitive neurodevelopmental hazard to humans”. Similarly, EPA mandates that chlorine be added to drinking water in order to reduce pathogenic bacteria, algae, and fungi levels. Nevertheless, one can easily find claims on the internet that chlorine in water causes cancer.


Some naturally occurring substances make their way into the water supply and must be filtered down to lower levels for safety. Radioactive radium is naturally present in rock, soil, and surface water and can be effectively removed from drinking water by a variety of methods, yet reports of elevated radium in drinking water alleged to be carcinogenic crop up periodically. Nitrates and nitrites, which in high levels cause the “blue baby syndrome” (methemoglobinemia), are another example of this phenomenon.


Finally, some substances may get into drinking water supplies from factory and mining discharges. Per- and polyfluoroalkyl substances (PFAS) are an example of a group of potentially toxic contaminants that are used in manufacturing and can wind up in drinking water. Perhaps the most famous such example is hexavalent chromium, the substance featured in the famous movie Erin Brockovich. In that movie, based on a real-life story, Brockovich links what she believed to be an unusual cluster of cancer cases in Hinkley, California to run-off of hexavalent chromium from a Pacific Gas and Electric plant.


         An examination of these claims reveals that high levels of contaminants in drinking occur infrequently, most often involving elevated levels of coliform bacteria that result in gastroenteritis. Often, the claims that something is carcinogenic in water turn out to stem from studies in rats and mice in which doses far higher than anything a human would ever consume are shown to cause cancer. In fact, such studies should reassure us that the level of contaminant in our water is safe: cancer in such instances can only be induced in rodents when doses are pushed to extreme levels that are far out of range for humans. For example, an often-cited study from the National Institutes of Health did show that hexavalent chromium causes cancer in mice and rats, given doses of chromium between 14.3 mg/L and 516 ml/L for two years. But the lower of these doses is still ten times higher than what humans could consume from the most highly contaminated water sources identified in California and only the highest doses actually caused cancer in the rodents.


The claim that chlorine when consumed in drinking water increases cancer risk seems to come mostly from the fact that chlorine does so when inhaled as poison gas used in warfare (now outlawed by international law). Evidence is actually weak that chlorine is carcinogenic in the concentrations EPA mandates for drinking water, and the risks of not chlorinating drinking water are deemed far greater than any increased risk of cancer. Nitrates and nitrites in drinking water were found to pose no human health risk in a careful analysis by the National Research Council.


A recent National Toxicity Program draft report on fluoride in drinking water raises concern about the compound’s potential to lower IQ in children. The draft report is based on an ongoing review of animal and human literature. Some recent studies have suggested a relationship between fluoride intake during pregnancy and by infants who consume reconstituted formula and lower IQ compared to those without fluoride exposure. Neither study authors called for ending drinking water fluoridation but rather called for a reduction in fluoride consumption by pregnant women and in infant formula, respectively. It is also important to note that the presumption that fluoride has neurodevelopmental toxicity is challenged by several other experts and is the subject of a current critical review by a committee of the National Academy of Sciences. Therefore, the final verdict on the National Toxicology Program’s draft report is unclear at this time.


The notion that drinking water fluoridation adversely affects IQ of course demands that we believe that the IQs of children born in most US cities and towns since the 1950s would be higher were it not for fluoride their mothers consumed while pregnant with them and that they later consumed themselves. Even the claims about chromium popularized by the Erin Brockovich movie now seem suspect. Some studies have found no increased rate of cancer in Hinkley in the time period covered by the movie. Independent scientists have also questioned the connection claimed in the movie between chromium and the various illnesses people in Hinkley reported having.


Finally, much of the insistence that our water is contaminated comes from the Environmental Working Group (EWG), a controversial organization that once helped spread the myth that vaccines cause autism. The EWG has set its own maximal levels for various potential water contaminants, usually lower than those set by EPA. EWG says that its “scientists reviewed the best and latest scientific evidence, legal standards and health advisories, and defined water quality goals that will truly protect public health.” Unlike EPA, EWG asserts that their standards take into account “heightened vulnerability of children, infants and developing fetuses to toxic chemicals” and also consider emerging potential toxicities for which there are as yet no EPA standards. Most of their standards are based on those of the California Office of Environmental Health Hazard Assessment. Some EWG skeptics complain that it has conflicts of interest because of involvement with organic product companies and that it promotes ideas and warnings of dubious scientific validity.

Overall, then, we are unpersuaded that substances present in the American drinking water supply that most of us consume pose significant health threats. That conclusion is challenged, however, by recent loosening of EPAs standards by the current administration. While we once could trust the EPA to be an impartial, scientifically-based regulatory agency, the basis for that trust has clearly been eroded in the last three years. But for now, it seems that the people most concerned about chlorine, PFAS, fluoride, and nitrates in water are affluent people who can afford to buy bottled water.


Lead Contamination is a Real Threat


         On the subject of lead contamination, however, we came to a different conclusion. The service lines that connect water mains to buildings, including homes, are often made of lead and very old (they were banned in 1986). Municipalities add compounds to the water that coat lead service pipes and prevent lead from leaching into tap water. This method is usually effective, but old pipes can still corrode and break and various factors like higher acid levels can erode the protecting chemical lining. Because of this, the EPA mandates regular testing of municipal water for lead and actions that must be taken if the level exceeds 15 parts per billion (ppb) in more than 10% of customer taps sampled. The most famous recent cases of lead contamination in drinking water occurred in Flint, Michigan and Newark, New Jersey.

The situation in Flint evolved when the city manager in a cost-cutting measure discontinued purchasing water from Detroit, which gets its drinking water from Lake Huron, and instead began pumping water from the Flint River. The water in the Flint River is more acidic than Lake Huron and eroded the coating on the water pipes that normally keeps lead from leaching into the water. Lead levels in the Flint drinking water were soon detected above the maximum EPA allowable limit. In addition, buildup of coliform bacteria around the aging pipes lead city officials to increase the amount of chlorine in the water.


This led to high levels of chlorine breakdown products called trihalomethanes, some of which are believed to be carcinogens. Flint has now resumed getting its water from Detroit.

A change in the source of water for Flint, Michigan led to an increase in lead levels that officials at first seem to have dismissed (source: Shutterstock).

What seems to have happened in Newark is that the city was adding sodium silicate to the water to prevent lead leaching from service pipes into the water, which was working. Then, in 2015, the city started changing the water’s acidity to deal with other potential contaminants and that prevented sodium silicate from working.  In 2016 the water in Newark started failing the EPA mandated lead tests on multiple occasions. The city began handing out water filters that had worked in Flint, but for unclear reasons did not in Newark and the city was forced to hand out bottled water. Newark recently announced a $120 million program to replace its lead pipes, but this is an expense a city like Newark will find hard to bear.


What happened in Flint and Newark are certainly not routine occurrences and each involved some degree of denial by public officials in the face of clear warnings that water quality had been compromised. But there is one thing that both cities have in common with each other and many other American municipalities: both cities are poor and largely populated by people of color. Lead pipes are mainly found in older cities and fears about water quality are justifiably high among African Americans and other minorities who live in them. These are precisely the communities that are most likely to lack money to replace old lead service pipes. Some low income communities do not even have the luxury of drinking water from a municipal supply: Millions of low income Americans still do not have access to potable water or drink water from contaminated wells. Thus, unlike affluent communities where the water is usually perfectly safe but people nevertheless can afford to buy bottled water, people in poor communities drink water pumped through aging infrastructure but may lack the financial and political resources to do anything about the problem.

Ironically, most of the bottled water people drink is just filtered tap water.


And not all of it is regulated; the Food and Drug Administration (FDA), not the EPA, regulates the quality of bottled water but only if it is shipped across state lines. Water bottled and consumed within a state may or may not be regulated by state authorities.

When Consumer Reports tested bottled water, they found higher levels of contaminants in some products than the EPA permits for the public tap water supply.

And of course, most bottled water comes in plastic bottles, a well-described environmental hazard.


  Thanks to a generous grant from the Robert Wood Johnson Foundation, Critica is now engaged in a project that is examining what people think and say about our drinking water. As we continue to research this area, it is likely that new facts will emerge and some of our conclusions may change. For now, however, we are convinced about several things: most people can safely drink tap water, without filters, right out of the faucet; bottled water is unnecessary and bad for the environment; and poor communities that cannot afford to replace aging lead pipes or purchase filters and bottled water are at risk for consuming higher than recommended amounts of lead in the public water supply. Here we have one more reason to call on our public officials to address the country’s infrastructure needs and income inequality issues. For some people, these are affecting the very water we drink. Perhaps if bottled water companies are making billions of dollars selling municipal tap water that taxpayers pay for, those companies should contribute funds to replace lead service pipes around the country so that even people who can’t afford their products can have safe water to drink.

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