How to Make Cold Brew Coffee in a Kilner® Jar: A Step-by-Step Guide

Cold brew coffee has become a favorite for coffee lovers who crave a smooth, less acidic, and naturally sweet cup. Unlike traditional hot brewing, cold brew steeps coarsely ground coffee in cold water for 12–24 hours, resulting in a concentrate that's perfect over ice or mixed with milk. And you don't need any fancy equipment—a simple glass jar, like the iconic Kilner® jar, is all it takes.

In this guide, we'll show you how to make cold brew coffee in a Kilner® jar, from choosing the right beans to straining and storing your concentrate. Whether you're a seasoned home barista or a curious beginner, this method is easy, affordable, and yields café-quality results.

Why Use a Kilner® Jar for Cold Brew?

Kilner® jars are perfect for cold brew coffee for several reasons. Their wide mouths make it easy to add coffee grounds and water, and the airtight seal ensures no fridge odors affect your brew. The glass material is non-reactive, so it won't impart any flavors to your coffee, and it's easy to clean. Plus, the classic design looks great on your counter or in the fridge.

For a standard batch, the Kilner® Round Glass Clip Top Preserving Jar, 1 Litre is an ideal size. It holds about 4 cups of liquid, which is perfect for a week's worth of cold brew. If you're brewing for a crowd, you can easily scale up using a larger jar.

• Wide mouth for easy filling and cleaning
• Airtight seal keeps coffee fresh and prevents odors
• Non-reactive glass preserves the true flavor of your coffee

What You'll Need

Gathering your supplies is simple. You'll need a Kilner® jar (like the 1 Litre clip top jar), coarsely ground coffee, cold filtered water, a scale or measuring cup, and a fine-mesh strainer or cheesecloth for filtering. Optional: a Kilner strainer funnel, stainless steel to make pouring into your storage bottle mess-free.

The coffee-to-water ratio is crucial for a good concentrate. For a standard strength, use 1 part coffee to 4 parts water (by weight). For a stronger concentrate, use 1:3. We recommend starting with 1 cup (about 100 grams) of coarsely ground coffee and 4 cups (about 950 ml) of cold water for a 1 Litre jar.

• 1 Litre Kilner® jar (or larger if needed)
• Coarsely ground coffee (avoid fine grind to prevent bitterness)
• Cold, filtered water
• Scale or measuring cup
• Fine-mesh strainer or cheesecloth
• Optional: Kilner strainer funnel for mess-free pouring

Step-by-Step: How to Make Cold Brew in a Kilner® Jar

Start by adding your coarsely ground coffee to the Kilner® jar. If you have a scale, weigh it for accuracy. Then, slowly pour the cold water over the grounds. Use a spoon to gently stir, ensuring all the coffee is saturated. This is called a 'bloom' in cold brew, and it helps extract flavors evenly.

Seal the jar with its clip-top lid and place it in the refrigerator. Let it steep for 12 to 24 hours. The longer it steeps, the stronger and more concentrated the brew. After steeping, strain the mixture through a fine-mesh strainer lined with cheesecloth, or use a coffee filter. You may need to strain twice to remove all the fine grounds.

The resulting concentrate can be stored in the refrigerator for up to two weeks. To serve, dilute with water or milk (typically 1:1) and pour over ice. You can also get creative with flavored syrups or spices.

• Steep for 12 hours for a milder brew, up to 24 hours for a stronger concentrate.
• Always use coarse grind to avoid over-extraction and bitterness.
• Filter twice for a cleaner cup.
• Store concentrate in a sealed Kilner® jar in the fridge.

Tips for the Perfect Cold Brew

The quality of your coffee beans matters. Choose a medium to dark roast for a rich, chocolatey flavor, or a light roast for a brighter, more fruity cup. Always grind your beans coarsely, just before brewing, if possible.

Water quality is also key. Use filtered water to avoid any off-flavors. And remember, cold brew is highly customizable—experiment with different steeping times, ratios, and even add a pinch of salt to enhance sweetness.

If you're making cold brew for the first time, start with a small batch using a Kilner® Storage Jar & Fine Grater 0.25 Litre. This size is perfect for testing ratios without wasting coffee. Once you've perfected your recipe, you can scale up to a larger jar.

• Use freshly ground, coarse coffee for the best flavor.
• Filtered water prevents impurities from affecting taste.
• Adjust steeping time to control strength.
• Try adding vanilla, cinnamon, or cardamom for a unique twist.

Serving and Storing Your Cold Brew

Cold brew concentrate is versatile. You can enjoy it black over ice, mixed with milk or plant-based alternatives, or even in cocktails. For a refreshing summer drink, add a splash of vanilla syrup and a dash of cinnamon.

To keep your cold brew fresh, store it in a sealed glass jar in the refrigerator. The Kilner® Round Glass Clip Top Preserving Jar, 1 Litre is perfect for this, as its airtight seal preserves flavor and prevents absorption of other fridge odors. For individual servings, consider using the Kilner® Round Twist Top Jar 43ml for small portions or for taking on the go.

• Dilute concentrate with water or milk to taste.
• Cold brew can be stored for up to two weeks in the fridge.
• Use smaller Kilner® jars for single-serve portions.

Making cold brew coffee in a Kilner® jar is simple, cost-effective, and yields a deliciously smooth concentrate that rivals any coffee shop. With just a few ingredients and a little patience, you can enjoy perfect cold brew at home. So grab your Kilner® jar, some quality coffee beans, and start brewing today!