The sight of cool water emerging mysteriously out of the deep-delved earth has long fascinated humans who once believed some springs were sacred, with the power to inspire poets or miraculously cure diseases.

Now some people believe that there are “probiotics” in water that comes straight out of the ground.

Rebranded as “raw water,” “live water,” “real water” or “unprocessed water,” untreated spring water is commanding a high price in places such as Silicon Valley, according to a New York Times article published in December.

The article noted that a grocery store in San Francisco frequently is selling out its stock of unfiltered, unsterilized spring water. A 2½-gallon container costs $36.99.

Raw water fans say they avoid municipal water — or “dead water,” as some call it — because they want water free of the chlorine and fluoride often added to tap water. Some argue that raw water has healthy bacteria.

“They’re nut cases. You can quote me on that,” said Stew Thornley, a Minnesota Health Department health educator. Thornley said tap water is the safest, most thoroughly tested water available.

Spring water, in contrast, is susceptible to contamination and can vary rapidly in quality depending on changes in the environment or land uses around the spring, according to the Health Department.

Dr. Donald Hensrud, medical director of the Mayo Clinic Healthy Living Program in Rochester, said he’s unaware of any health benefits of untreated water. But there are some health risks, such as the potential presence of nitrates or giardia.

“People have this idea that natural is better with regard to water,” Hensrud said. “It’s kind of analogous to the immunization issue.”

Thornley said, “We definitely don’t recommend this raw water movement.”

That isn’t deterring fans of the Fredrick-Miller Spring in Eden Prairie, a historic spring converted into a free public tap on land owned by the city.

Vehicles frequently line up in the small parking lot next to the constantly flowing outdoor spigot as people fill up their jugs and water bottles despite a city sign nearby warning: “The quality of the water from this spring can change quite rapidly so even though the water is tested, we cannot assure its safety at all times.”

A recent test of the spring showed low levels of nitrate, no bacteria and some naturally occurring fluoride. But the water at the Fredrick-Miller Spring is tested only once a month, said Rick Wahlen, the city’s utilities manager. Municipal water systems are tested much more frequently.

Still, spring water fans say it tastes better than tap water, that it makes better coffee, pasta or home-brewed beer and that even their plants and pets prefer it.

“It’s pure, pure, pure,” said Kevin Thoresen, a Shakopee resident who recently filled up bottles with water from the spring. He said he uses the spring water, which he stores in brown glass bottles, to properly make Essiac tea, an herbal tea used by some as an alternative treatment for cancer.

“You’re talking cancer? I’ve had it three times,” said Marilyn ­Schroeder, a St. Louis Park woman who also was waiting to fill her water bottles at the spring. “I do not drink city water. I don’t believe in fluoridation.”

Mark Olson, of Big Lake, another spring water fan who has read about “structured water” and the “fourth phase” of water, said, “Everybody I’ve met just believes it’s very healthy water. I feel good when I drink it.”