Written by Erin Meister via seriouseats.com
Iced coffee is one of the purest pleasures of summer. Short of a soft-serve ice cream cone, it pretty much is the one edible item that represents the season for me. Which makes it all the more tragic when something's just not right. Sometimes the brewing recipe is off, or the coffee's old, sure. But sometimes the promise of a refreshing cup of iced coffee is undone by the very thing that makes it so appealing in the first place: the ice.
Whether you cold brew, hot brew over ice, or however you like to make your chilled coffee, give your ice a second thought by following a few quick suggestions, and you'll be back on the road to caffeinated summer fun in no time.
Think about it: When's the last time you did this? When's the last time I did this? Even in the seemingly safe, enclosed environment of a freezer, all kinds of dust and crud can float around, landing in the empty spots of your icecube tray. (I never consider, for instance, that the bags of frozen berries I toss in next to my cubes might be covered in dust from transit or store shelves. Gross!)
At least once a week, give your trays a good, solid scrubbing before refilling them and putting them back. I'll try to make the same pledge, because I totally just grossed myself out even thinking about it.
Additionally, ice picks up odors and flavors easily, especially in an environment without a lot of temperature stability—e.g. if you open and close the freezer door often, or cram the ice box so full it has a hard time cooling down. Keeping the walls and shelves of the freezer clean, and storing other foods in air-tight containers, can prevent your ice cubes (and, therefore, your iced coffee) from tasting like leftover matzoh ball soup.
Freezer burn is no bueno.
The trays that your fridge came with might be fine for any run-of-the-mill glass of water, but if you're serious about iced coffee you might do yourself the favor of upgrading.
For one thing, try to find trays designed to make cubes the equivalent of 1 fluid ounce of water, for an easier conversion when making iced coffee. Or go cocktail-fancy with some specialty trays, like these giant silicone molds, which make six 2-inch square cubes. You can also get cute and buy these coffee-bean-shaped molds, even freezing a little bit of iced coffee in them to make meta cubes. Whatever makes you happy!
Don't, however, feel locked into using whatever you happen to have around. You're worth a better iced-cube tray!
The water you drink at home, and even brew your coffee with, might be fine enough for those purposes, but sometimes in its frozen state water can taste sort of grody. The metallic twang of tap water or the slight pool smell of chlorine might come through more, and will therefore only add funky tastes and smells to your iced cubes.
Try using a water filter when making iced cubes, and see if it makes a difference in your iced-coffee experience, even if you don't brew with it.