Mr. Battle poured himself a glass. “The water from the tap just doesn’t taste quite as refreshing,” he said. “Now is that because I saw it come off the roof, and anything from the roof feels special? Maybe.”

The most prominent proponent of raw water is Doug Evans, a Silicon Valley entrepreneur. After his juicing company, Juicero, collapsed in September, he went on a 10-day cleanse, drinking nothing but Live Water. “I haven’t tasted tap water in a long time,” he said.

Before he could order raw water on demand, Mr. Evans went “spring hunting” with friends. This has become more challenging lately: The closest spring around San Francisco has recently been cut off by landslides, so reaching it means crossing private property, which he does under cover of night.

“You have to be agile and tactile, and be available to experiment,” he said. “Literally, you have to carry bottles of water through the dark.”

At Burning Man, the summer festival in the Nevada desert that attracts the digerati and others, Mr. Evans and his R.V. mate brought 50 gallons of spring water they had collected. “I’m extreme about health, I know, but I’m not alone with this,” Mr. Evans said. “There are a lot of people doing this with me. You never know who you’ll run into at the spring.”

The founder of Live Water, Mukhande Singh, started selling spring water from Opal Springs in Culver, Ore., three years ago, but it was a small local operation until this year. Marketing materials show Mr. Singh (né Christopher Sanborn) sitting naked and cross-legged on a hot spring, his long brown hair flowing over his chest.