Measure out one cup of coffee beans and grind them on the coarsest setting your grinder allows. The grounds should look like chunky breadcrumbs or sea salt, not powdery.

Find a clean glass jar that holds at least 32 ounces and has a tight-fitting lid. Make sure it's completely dry inside, then set it on your counter.

Pour the coarsely ground coffee directly into your prepared jar. Tap the jar gently on the counter to settle the grounds slightly, but don't pack them down.

Slowly pour four cups of cold filtered water over the grounds, making sure all of them get wet. Stir gently with a long spoon for about 30 seconds to ensure the grounds are fully saturated.

Put the lid on your jar and place it in a cool location, such as your kitchen counter or inside a cabinet. Let it steep for 12 to 24 hours.

After the steeping time is complete, place a fine mesh strainer over a clean bowl and line it with cheesecloth or a cloth filter. Slowly pour the mixture through the filter to catch all the grounds, letting gravity do the work without squeezing or pressing.

Pour the strained liquid through a fresh paper filter or cloth filter one more time to remove any remaining fine particles.

Use a funnel to pour your finished concentrate into clean glass bottles or jars with tight lids. Label each bottle with the date and store it in your refrigerator for up to two weeks.