New York City's first water-only café in Manhattan, called Molecule, serves filtered tap water to discerning water drinkers for $2.50 a glass plus tax.
If you bring your own container, the water costs just $1 for up for 50 ounces.
The owners insist their filtered water isn't just any old tap water.
"They say the water streams through a $25,000 filtering machine that uses ultraviolet rays, ozone treatments and reverse osmosis in a seven-stage processing treatment to create what they call pure H20," Sophia Hollander writes in the Wall Street Journal.
"I mean it's subtle, but if you have a sensitive palate you can totally tell," says co-owner Adam Ruhf.
Molecule has plenty of critics. Steve Cuozzo of the New York Post says he prefers the taste of both tap and bottled waters over Molecule's improved water and claims only those "who belong to the High Holy Church of Culinary Rectitude" would waste their money at the café.
Jen Doll of The Atlantic Wire isn't convinced either.
"Point is, do you want to pay $2.50 plus tax for a 16-ounce bottle of what you can get—minus the process, of course — out of your tap, or pour out of your own Britta, or glug from a bottle of Poland Spring you got for a buck at the bodega? Do we need fancy water (of course not) any more than we need fancy air?" she writes.
Ruhf seems unfazed by the criticism.
"We are trying to change the way people think about water," he says.
He and his business partner, Alexander Venet, are adamant that New York City's water, despite being a source of local pride, is not as great as its advertised to be.
"I don't want chemicals in my water. I don't even want chlorine in my water. Chlorine is like bleach. Do you want to drink bleach? No one wants to drink bleach. So that's my opinion on New York tap water," Ruhf tells the Wall Street Journal.
Rufh credits the healing properties of purified water for his recovery from two painful car accidents and the inspiration for the start-up.
"It's more of an intuitive thing about cleanliness," he explains to DNAinfo. "Not wanting toxins [from unfiltered water] to further inhibit my recovery."
A spokesperson for the New York City Department of Environmental Protection defends the city's water.
"Public health experts agree that New York City tap water is among the safest, highest quality in the world, a standard we confirm through more than 500,000 tests each year."
Molecule Water Café may be the first of its kind in New York, but it's not the first café to try to make water the main draw.
In 1987, The Water Bar opened on Rodeo Drive in Beverly Hills, offering bottled water from 25 countries. In 2008, Melbourne's Smart Water Bar opened as a late-night spot offering hydration long after bars stop selling alcohol.
Would you pay for ultra-purified water?