Having already scrutinized the properties of various spirits, bitters and sweeteners, bartenders are now turning their attentions to the ingredient which takes up the most space in a cocktail glass: Water.

In July, at this year’s Tales of the Cocktail conference in New Orleans, bar luminaries including San Francisco bartender-turned-brand ambassador Neyah White and cocktail writer Dave Wondrich publicly urged their peers to put more water in their drinks. Although they didn’t delve too deeply into the chemistry, they obliquely referenced the atomic changes which occur when liquor’s diluted: As food scientist Harold McGee explained in a 2010 New York Times article, aromatic molecules cling tightly to alcohol molecules. When water’s added to the mix, those molecular life rafts become more spaced out, forcing aromas out of the glass and up into the drinker’s nose.

Whiskey connoisseurs have long been in the habit of adding a drop of water to their tipples. But Kara Newman, spirits editor for Wine Enthusiast and author of two cocktail books, suspects the recent obsession with water is an outgrowth of a newer trend. According to Newman, bartenders have lately been thinking hard about ice and dilution.

“A couple of years ago, we started with bars thinking about the form of ice, whether it was big, rounded spheres for whiskey drinks or pebbled ice for tiki drinks,” she says. “If you have a very strong tiki drink, pebbled ice melts more quickly and dilutes the drink. And if you wanted no dilution, you’d add something like those awful whiskey rocks.”

Now, Newman says, bartenders are debating whether the water added to drinks, whether in ice or liquid form, should originate from the same area as the spirit. After all, if Kentucky distillers make such a big deal about the limestone water that’s the foundation of their bourbon, should bartenders sully it with what flows from a South Carolina tap? Quality aside, mixing waters of different provenance could amount to aesthetic dissonance — or at least that’s the argument the limestone spring water sellers are making.

Newman’s not aware of many craft bartenders significantly upping the water content of their cocktails for art or profit. “If you have someone who’s diluting drinks just to make a buck, you should go to another bar,” she counsels. But she says there is increased interest in “lower-octane” cocktails, which may help explain the wave of pro-water sentiment at Tales, traditionally a highly soused affair.

“People are looking for less buzzy drinks,” Newman says. “People want to have more than one and not be blasted out of their minds.”

Reach Hanna Raskin at 937-5560.