When food-safety expert Bill Marler saw The New York Times' trend piece on Silicon Valley's recent obsession with raw water, he thought he was reading a headline from The Onion.

According to The Times, demand for unfiltered water is skyrocketing as tech-industry insiders develop a taste for water that hasn't been treated, to prevent the spread of bacteria or other contaminants.

In San Francisco, "unfiltered, untreated, unsterilised spring water" is selling for as much as US$60.99 for a 2.5 gallon (9.5 litre) jug. Startups dedicated to untreated water are popping up.

People - including startup Juicero's cofounder Doug Evans - are gathering gallons of untreated water from natural springs to bring to Burning Man.

Tourmaline SpringTourmaline Spring sells an untreated water as "sacred, living water." (Tourmaline Spring)

While Evans and other fans say raw water is perfect for those who are "extreme about health," Marler - a food-safety advocate and a lawyer - says the opposite is true.

"Almost everything conceivable that can make you sick can be found in water," Marler told Business Insider.

Unfiltered, untreated water, even from the cleanest streams, can contain animal feces, spreading Giardia, which has symptoms such as vomiting and diarrhea and results in roughly 4,600 hospitalisations a year.

Hepatitis A, which resulted in 20 deaths in a California outbreak in 2017, can be spread through water if it isn't treated. E. coli, and cholera can also be transmitted via untreated water.

Because filtered, treated water has become the norm, Marler says, most people don't realize how dangerous so-called raw water can be.

"The diseases that killed our great-grandparents were completely forgotten about," he said.

Most Americans don't personally know anyone who died of Hepatitis A or cholera, thanks to advances in technology and more stringent safety standards.

As a result, they had a hard time realising the risks involved in consuming untreated water.

"It's fine till some 10-year-old girl dies a horrible death from cholera in Montecito, California," Marler said.

On January 2, Business Insider's Melia Robinson visited a San Francisco supermarket where a small company called Live Water sells its untreated water.

Rainbow Grocery was sold out of the Fountain of Truth Spring Water from Live Water, but a sign indicated a "slight price increase".

raw water live water san francisco 5(Melia Robinson/Business Insider)The cost of a 2.5 gallon jug increased from US$36.99 to US$60.99 since The Times' article published. While the price includes the glass container, a refill costs only US$14.99, according to The Times.

According to Marler, the raw-water trend is similar to people's obsession with raw milk or opposition to vaccines.

While they lack scientific evidence, they're convinced that they are correct, in part because they have failed to see the repercussions of life without scientific advances.

"You can't stop consenting adults from being stupid," Marler said. "But we should at least try."

This article was originally published by Business Insider.

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