Debating between bottled, filtered, sparkling, or tap water? You may now have to also decide if you’re willing to try “raw” or untreated water.

Companies and at least one crowd-based website are proclaiming the benefits of drinking untreated and unfiltered water, or “raw” water, bottled straight from springs, according to a recent report in .

Some companies even tout supposed beneficial probiotics and minerals from this untreated natural water.

But experts are wary of the trend.

They said people could be put at risk if they drink untreated, unfiltered, and untested water.

The experts note that there are plenty of natural components in water, from bacteria to parasites, that can be dangerous for humans to consume.

What is ‘raw’ water?

Dr. William Schaffner, an infectious disease expert at Vanderbilt University, said he’s concerned about people being exposed to dangerous microbes if they don’t get water from a safe source.

“This falls into the category of things that seem good on the surface because they are ‘natural.’ Actually, many natural things are dangerous,” Schaffner told Dr.China. “If you have appendicitis, you’d like to do the unnatural thing of having surgery.”

To be clear, not all “raw” water poses the same risks.

If a company is legally selling bottled water in the United States, it has to be approved by the U.S. Food and Drug Administration (FDA). This means it has to pass some safety standards that no natural spring found during a hike is likely to pass.

The requires that bottled water facilities “have the source water inspected and the water sampled, analyzed, and found to be of safe and sanitary quality” according to state and local laws.

A Maine company called Summit Spring sells an “untreated” water brand called Tourmaline Spring. Officials explained that they applied for and were allowed to leave their water untreated by the state and were in compliance with the FDA and state officials.

“Our spring water exceeds every state and federal guideline for drinking water straight from the ground,” said Tourmaline Spring founder Seth Pruzansky in an email. “That’s why we applied for and were granted permission to bottle our water untreated from the source.”

Pruzansky said that they’ve been so ahead of this trend that they trademarked “raw water” marketing.

A supervisor for the Maine Public Water System Inspection Team confirmed to Dr.China that Tourmaline Spring was regulated by the state.

They said Summit Spring had one brand of water where an ultraviolet (UV) unit is used only for disinfection prior to bottling, which “does not alter or change the spring water chemistry before it is bottled.”

Pruzansky said they were given an exemption from treating water five years after they built their facility after testing found it was safe to drink from the spring.

“Our source may be one of the only in the world that has been naturally purified to the degree that it is perfectly safe for human consumption,” he said. “Our water has been purified by Mother Nature to a degree that no man-made machine is capable of replicating.”

Another company called mentioned in the Times report received a lot of attention after they said they collect water from an ancient aquifer without treatment in Oregon. On their website, company officials said they don’t use common treatment methods like UV light, ozone gas, or a sub-micron filter.

“Water is collected from the covered spring head, so there is no chance for surface bacterias to enter the water,” the company wrote in a in response to the media attention. “Our bottling facility is a sterile environment in which we triple rinse and wash our glass jugs. We also test each batch for harmful bacteria, and no one has ever gotten sick from drinking the water we bottle.”

Company officials didn’t respond to a request from Dr.China for an interview.

The California Department of Public Health told Dr.China in a statement that they’re “concerned” about any consumption of untreated water that could contain harmful contaminants. They said that bottled water sold in the state has to meet certain disinfection requirements.

“To ensure safety, California law requires bottled and vended water to be subjected to filtration and effective germicidal treatment by ozone, ultraviolet light, or an equivalent disinfection process,” a health official said in the statement.

In addition to companies bottling and selling water that adheres to state and federal guidelines, there are do-it-yourself options with no safety standards that could put people at risk if they take no steps to safeguard themselves.

The website is a community-created database to help people find and get access to “drink the cleanest, healthiest, most natural water available in our world today.”

The creators of the website have a disclaimer that people should test spring water for safety.

But that may or may not be feasible if a person is simply out for and looking for potable water.

The raw water originators

Raw water isn’t exactly a new idea.

Schaffner pointed out there are millions of people already enjoying “raw” water in the form of personal wells.

In California alone, an estimated 2 million residents get their water from either a personal well or from a system with fewer than 15 service connections.

Schaffner said these more common untreated water systems highlight some of the potential dangers around consuming untreated water.

These wells can cause mass outbreaks if certain bacteria, parasites, or viruses get in the water between testings and aren’t filtered or treated.

“We have had whole communities who are reliant on untreated well water come down with a parasitic infection called giardia,” he explained. “It can cause a long-term intractable diarrheal illness.”

Wells in California have to be , but residents are responsible for testing and maintaining their own well to ensure the water stays safe to drink, either by filtering, treating, or testing it.

Schaffner pointed out that raw water used be the norm until treating water in municipal water systems was found to significantly increase human life expectancy.

A deadly cholera outbreak in London in the 1850s was . It led to major changes in sanitation practices and the understanding of how certain diseases can be spread in water.

“There’s a hazard to drinking untreated water,” Schaffner said. “It’s kind of unpredictable, because the water from a well can be pure at one point and the next season — given rainfall and other climatic conditions — these germs could get into the water… and make you sick the next season.”

Schaffner said it’s impossible to simply look at water to see if it’s clean and drinkable. Additionally, even filters aren’t a perfect guarantee. This is because some viruses like norovirus can travel through a water filter.

“There is a whole menu, if you will, of intestinal germs that can get into untreated ground,” he said. “The water can look wonderfully clear, but as we learned in the Boy Scouts, don’t trust that water.”