Let's state the obvious here: Water treatment removes bacteria, parasites, pesticides, and other contaminants, and drinking untreated water come with serious risks.
In the United States, the Environmental Protection Agency, via the Safe Drinking Water Act, originally passed in 1974 (and updated since), sets health guidelines for the public wells, reservoirs, and springs many Americans rely on. Overall in the US, outbreaks from water-associated diseases are low. A CDC report released this year calculated 42 drinking water–associated outbreaks in 2013-'14, which caused 1,006 cases of illness, 124 hospitalizations, and 13 deaths. (The majority of the cases, and all of the deaths, were linked to Legionella,which causes Legionnaire's disease — spread through inhaling the bacteria.)
Meanwhile, in the developing world, access to clean and sanitary water is a huge public health and human rights issue. Water-associated diseases such as cholera are still global threats. In 2017, an outbreak of cholera — which is spread by drinking water or eating food contaminated with a certain bacteria — reached 1 million suspected cases in Yemen, where a devastating famine has prevented access to clean water.
It is true that the United States has issues with its public water systems because of its aging infrastructure. The EPA has estimated the country will require a $384 billion investment in local water systems in the coming years to maintain clean water standards. And as many as 10 million lead pipes could still be in use, though Congress banned them three decades ago, according to the New York Times. The risks of lead leaching into water are legitimate — as the crisis in Flint, Michigan, proved in heartbreaking detail. Experts point to crumbling infrastructure, and the lack of resources to fix it, as contributing to the water-associated disease outbreaks that the US does experience.
But that doesn't make the case for "raw water." It's an argument to reinvest in and improve the water infrastructure that already exists in the United States, particularly in rural and low-income areas that don't always have the resources to replace aging pipes or treat water as robustly as it needs to be.
The "raw water" trend might be fleeting — the appeal of potentially drinking animal pee could wear off — but it has something in common with other pseudoscientific theories that see "natural" as good and "chemical" as bad.
The motive that drives people to seek out possibly polluted spring water is a more extreme version of the same beliefs that drive everything from fears over GMO foods to more dangerous practices such as the anti-vaccination movement. Engaging in these bogus practices sometimes does nothing more than needlessly drain your wallet, but others could pose health consequences. Those who choose not to vaccinate, for example, despite the ample science that backs up vaccines' value, put the most vulnerable at risk by sacrificing herd immunity.
As James Hamblin writes at the Atlantic about the "sanctimony" of the natural, "people use biological arguments to justify the same belief that has been around since the beginning of time: New things are unnatural and dangerous. Stuff was better before."
There is also the reality that modern medicine hasn't always fulfilled its promises. As Vox's Julia Belluz wrote about Goop's ability to galvanize its fans despite critical and scientific debunking, the appeal of a natural cure-all deeply appeals to people:
Traditional medicine has failed people in many cases, and often lacks solutions for the most common health woes — chronic pain, obesity, Alzheimer's. You need not look any further than the raging opioid epidemic to find cases where medicine has also done more harm than good.
And it is hard to persuade people that they're wrong once they're sure fluoride is a government attempt at mind control. People tend to rally around their beliefs once they're convinced of their authenticity, regardless of facts. Sometimes those false beliefs become deeply held because they offer a satisfying explanation that otherwise wouldn't exist — vaccines cause autism, for example — and other times it's because they match up with values, such as personal liberty.
The bigger problem isn't in convincing the raw water enthusiasts, or those who worry about GMOs, that they're wrong. It's that these ideas tend to migrate from the margins and cast doubt among the general public. The anti-vaccine movement offers an example of this: Vocal anti-vaxxers are likely a smaller group compared to people who are influenced by those views. They still generally believe in the benefits of vaccines, but they may delay or skip certain immunizations because of concerns that they're too much or unnecessary.
The "raw water" movement might be a passing fad. But sowing skepticism about water infrastructure or the importance of treated water is worrisome — and could have real consequences. According to Business Insider, the price of one brand of raw water has already doubled. It's now going for $60.