If you add water to whiskey, it may seem like a counterintuitive idea. After all, most things would be watered down by the presence of H20. But if you’ve ever enjoyed a taste-testing with a master distiller, you may have noticed at some point that he added a couple of drops of water to the glass. Doing so is said to open up the flavors and aroma of the drink. Even the word “whiskey” stems from the Gaelic word “uisge,” meaning “water.”

True whiskey connoisseurs might still be skeptical, so what gives? Is adding water to your whiskey just an urban legend or does science back this theory? Science says you should add water to your whiskey. Here’s why.

First, Why Water is a Key Whiskey Ingredient

Just three ingredients are needed to make whiskey: water, barley (or other types of grain) and yeast. The kind of grain used varies with the different types of whiskey being made, but all whiskeys need a small amount of malted barley to begin the fermentation process.

The water you use for whiskey is often considered the most important factor in making a good whiskey. For many distilleries, a unique water source is a point of pride. Whether it be a Scottish loch or an alpine river, a distillery’s water source is often as big a part of the brand identity. Clean, clear and free of bad-tasting impurities like iron are the driving factors in selecting water for whiskey.

Kentucky, as well as Maryland, Pennsylvania and Indiana, is an area rich with limestone so water there contains carbonates, which means the water source can have an important impact on flavor. For example, soft water can produce heavier whiskey, while hard water may produce lighter, sweeter spirits. Water with higher levels of organic matter can produce fruitier flavors in a finished whiskey. Because of the importance of water in how whiskey is made, a large number of distilleries are located next to a river or lake.

The Scientific Reason You Should Add Water to Your Whiskey

While water is a main ingredient initially, it’s also key to the rest of the manufacturing process. After the distilling step, water is added to reduce the alcohol content down to either 50-60 percent for American whiskey or 65 percent or higher for Scotch whisky. American whiskeys are aged in warmer, drier conditions so they lose water and increase alcohol content. Scotch whiskies are aged in cool, wet conditions so they absorb water and become less alcoholic.

The mixture of water, alcohol and congeners react with each other over time. These ingredients then react with oxygen in the outside air through oxidation. Aging whiskey in wooden barrels allows the water to move back and forth within the pores of the wood, absorbing substances within it and adding flavor to the finished product. And even though whiskeys are already diluted below 45 percent ethanol (alcohol), adding a few drops of water to your glass to dilute it even more can help the overall flavor by encouraging the other chemicals to evaporate, enhance the aromas and produce a whiff of flavor each time you take a drink. Or in other words, further diluting your whiskey with water once it’s in your glass will increase the boldness of the flavor.

Exactly How Much is Too Much?

Science aside, the water debate really boils down to a personal choice. Legendary bourbon distiller, Pappy Van Winkle, would tell you you’re crazy for even bothering with water. If it were up to him he’d add whiskey to the water and not the other way around. “That way you make a poor thing better rather than a fine thing worse,” he famously reasoned. He also believed 50 percent ABV (100 proof) was the ideal alcohol concentration for whiskey.

If you do want a splash of H20, the first step in deciding how much to add is to figure out the whiskey proof that you most enjoy personally. Some people pour their whiskey and add a couple of splashes. Others like to add a drop or two in through a dropper to open up the flavors. You can certainly wing it but more precision can offer increased benefits.

Once you find your ideal proof, start with a standard serving size, like 2 ounces. Measure out an amount of water to start with. Add small amounts of the water to the whiskey and then taste it. Keep repeating this step until you arrive at a taste you like. And then take note of how much water you’ve added so you can repeat this process in the future. With bourbon, you can dilute up to a 1:1 ratio (equal parts whiskey and water) because the flavor is robust to begin with.

Here’s an easy formula to for determining your ideal proof to water ratio:

• Amount of whiskey divided by water plus the amount of whiskey times bottle proof equals your ideal proof.
• Concrete example: If you start with 2 ounces of 100 proof whiskey and add ½ an ounce of water, your ideal whiskey is 80 proof. (2/2.5 x 100 = 80).

The Temperature of Your Water Matters, Here’s Why

Did you know the temperature of your water matters? To get the most flavor out of a glass of whiskey, the water temperature might be the most important point yet. The expert consensus is: room temperature water is better! Here’s why: sweet and bitter flavors change depending on the temperature of the water. The colder it is, the less those flavors come through.

To get the most nuanced flavor out of a glass of whiskey, drink it at room temperature, between 60 to 65 degrees Fahrenheit. In that temperature range, the most subtle, complex flavors will take center stage. And while more delicate flavors are best enjoyed at room temperature, drinking whiskey in a cocktail or on the rocks can lessen the harsh edge of this booze, which makes slow sipping more enjoyable for many.

There you have it! The scientific reason for why water belongs in your whiskey. If you’re looking for an easy way to test this water theory out yourself, Barrel Global offers anyone the opportunity to purchase full barrels of whiskey from leading distilleries around the world.

We’re on a mission to make whiskey barrel ownership accessible to collectors worldwide. As the first ever global marketplace for whiskey barrels, you can connect with distilleries and collectors around the world to build your own portfolio. For a whiskey experience unlike any other, request access today.

‍