How much water should you add to a pre-batched cocktail?

Dave Arnold (image courtesy MOFAD)

Dave Arnold (image courtesy MOFAD)

This is a question I grappled with throughout the recipe-testing process for Cocktails for a Crowd.  It might seem like a trifling matter — but you’d be surprised how much it impacts a cocktail. The right amount of water makes a cocktail better — that’s one of the reasons we add ice to drinks.

Although I ultimately landed on adding about 25% to 30% water to simulate the effect of melting ice, as usual, Dave Arnold figured out a more precise way to figure out the right amount of water to add.

And he figured it out years before I did.

If you don’t already know Arnold, he’s the poster boy for better cooking (and drinking) through chemistry. He’s the mastermind behind Booker & Dax, a chemistry lab-turned-cocktail bar. He’s also one of the driving forces behind the Museum of Food and Drink (MOFAD) — an enterprise I’m excited about– and hosts the longtime “Cooking Issues” podcast on Heritage Radio Network.

During a 2010 episode of Cooking Issues, Arnold tackled the topic of how much water to add to a pre-batched cocktail. Not only that, he compared how to handle drinks that are traditionally shaken vs. those that typically are stirred. “It’s hard to pre-batch a shaken cocktail,” he admits. “You really do need to shake it to get the texture right.”

Of course, his mad-scientist approach involves using liquid nitrogen to dilute the drink and still get the properly aerated texture that shaking provides. Most home bartenders, of course, aren’t about to start fiddling with liquid nitro. “If possible, choose a stirred drink to pre-batch,” Arnold concludes.  (I agree — but then again, I might be up for replicating shaken drinks for 20 people, where he would be replicating them for a “crowd” of 200 guests.) Here’s how Arnold determines how much water to add:

Make a single drink, using volume, the way you normally would, with jiggers. Weigh it on an accurate scale. Write the number down, that’s how much drink you’re starting with. Add your ice, stir it, then strain it. Now weigh how much the drink weighs now. That’s the weight of the total cocktail. Subtract the weight of the liquor you used from the total weight of the cocktail, and that’s the amount of water you should add. That’s the way to do it, instead of guessing in your head at 25%. If you just add water at room temp and taste it – When you chill it, the balance will be off.

It may seem tedious, but Arnold notes that you only need to do it once – if you get it right and write the recipe down, you don’t need to re-test it every time. And as Arnold says, “Your pre-batched drinks will thank you for it.