How to Make Cold Brew Coffee at Home
Cold brew is one of the simplest ways to get a great cup of coffee — no espresso machine, no fuss, just time and good beans. The method produces a concentrate that is smooth, low in bitterness, and naturally sweet, making it an excellent choice for warmer months or for anyone who finds hot-brewed coffee too sharp or acidic.
This guide walks you through everything: the right equipment, grind size, brewing ratio, steep time, and how to serve and store your cold brew. We also recommend two Indonesian single-origin coffees from Ariga that are ideally suited to the cold brew process.
Why Cold Brew Tastes Different
Temperature plays a significant role in how coffee extracts. Hot water pulls out soluble compounds quickly, including acids that give coffee its brightness — and, when over-extracted, its bitterness. Cold water extracts far more slowly and leaves many of those acidic compounds behind. The result is a concentrate that is noticeably smoother and sweeter than the same beans brewed hot.
This is also why bean selection matters more with cold brew than most people expect. Coffees with a bold, full body and naturally low acidity — such as wet-hulled Sumatran and natural-processed Javanese origins — perform exceptionally well when brewed cold. They hold up to the dilution of ice or milk without losing their character.
What You Need
Equipment
- A large jar or jug — a one-litre mason jar or a French press works well. No specialised cold brew equipment is required.
- A fine mesh strainer or coffee filter — to strain the grounds after steeping. A paper filter produces the clearest result; a mesh strainer is faster and leaves a slightly richer texture.
- A burr grinder — coarse, consistent grinding is essential. A blade grinder produces uneven particle sizes, which leads to over-extraction and bitterness even in cold brew.
- A second jug or bottle — for storing the finished concentrate in the fridge.
The Right Coffee
For cold brew, you want beans with a bold flavour profile and low acidity. Two Ariga single origins stand out for this purpose:
- Mandailing — sourced from North Sumatra, this coffee is processed using the wet-hull (Giling Basah) method unique to Indonesia. It delivers a heavy body, earthy depth, and a natural sweetness that comes through beautifully in cold brew. Low in acidity, it requires no sweetener and holds up well to ice and milk.
- Gayo — grown in the highlands of Aceh, Gayo has a clean, syrupy body with subtle chocolate and herbal notes. It is slightly more refined than the Mandailing and a good option if you prefer a smoother, more delicate cold brew.
Both are available in our Single Origin collection. If you prefer a more rounded, approachable result, our Blends collection also works well for cold brew.
Step-by-Step Cold Brew Method
Step 1 — Grind Your Coffee Coarse
Set your burr grinder to a coarse setting — roughly the consistency of raw sugar or coarse sea salt. This is significantly coarser than you would use for a French press, and much coarser than espresso.
A coarse grind is critical in cold brew. Because the coffee steeps for an extended period, a finer grind will over-extract and introduce bitterness even in cold water. When in doubt, grind coarser rather than finer.
Step 2 — Measure Your Ratio
The standard cold brew ratio is 1:8 coffee to water by weight for a concentrate that is served diluted, or 1:12 for a ready-to-drink strength. A reliable starting point:
- 60g of coffee to 500ml of water — produces a strong concentrate (dilute 1:1 with water, milk, or ice before serving)
- 50g of coffee to 600ml of water — produces a ready-to-drink cold brew at medium strength
Start with the concentrate ratio and adjust to taste. Cold brew is forgiving — small changes to the ratio have a noticeable impact on strength but not on quality.
Step 3 — Combine Coffee and Water
Add the ground coffee to your jar or French press. Pour filtered, room-temperature water over the grounds slowly, making sure all the coffee is saturated. Stir gently to ensure even wetting. Do not use hot or warm water — this defeats the purpose of the cold brew method.
Step 4 — Steep (Cold or Room Temperature)
You have two options for steeping:
- Cold steep (in the fridge): 18 to 24 hours. This is the standard method and produces a clean, mellow result. It is also the safest approach from a food safety perspective.
- Room-temperature steep: 12 to 16 hours. This extracts slightly faster and can produce a bolder, more intense concentrate. Keep the jar covered and steep out of direct sunlight. Strain promptly at the end of the window and refrigerate immediately.
Either method works well with Mandailing or Gayo. The room-temperature steep will bring out more of the earthiness in the Mandailing; the cold steep will highlight the cleaner chocolate notes of the Gayo.
Step 5 — Strain
Once steeping is complete, strain the coffee slowly through a fine mesh strainer lined with a paper filter, or press the plunger on your French press. Pour the strained concentrate into a clean jug or bottle. Discard the grounds.
If the liquid appears cloudy after straining, let it settle for five minutes and strain a second time. Cloudiness does not affect the flavour, but a clean concentrate stores better and looks better in the glass.
Step 6 — Serve
Cold brew concentrate is versatile. Some ways to serve it:
- Over ice: Pour 80–100ml of concentrate over a full glass of ice. Top up with cold water to taste.
- With milk or oat milk: Dilute 1:1 with your milk of choice. Mandailing in particular works exceptionally well with oat milk — the earthy, full-bodied character pairs with the natural sweetness of the oat.
- Straight: If you brewed at the 1:12 ratio, you can drink it directly from the fridge without dilution.
- As an iced latte base: Use the concentrate in place of espresso for a smooth, low-acid iced latte.
Step 7 — Store
Transfer any unused concentrate to an airtight bottle or jar and refrigerate immediately. Cold brew concentrate keeps for up to 10 days in the fridge. Ready-to-drink cold brew (already diluted) is best consumed within 3 to 4 days.
Do not leave cold brew at room temperature after brewing. Once strained, it must be kept cold.
Tips for a Better Cold Brew
- Use filtered water. Cold brew has nowhere to hide off-flavours. Tap water with a strong chlorine or mineral taste will affect the final cup. A basic water filter makes a noticeable difference.
- Grind just before brewing. Pre-ground coffee loses volatile aromatics quickly. Grinding fresh — even just an hour before brewing — improves the clarity and depth of the finished concentrate.
- Keep your equipment clean. Any residual oils or old coffee in your jar or grinder will affect the flavour. Rinse thoroughly before each brew.
- Label your batch. If you brew regularly, mark the date on the bottle so you know how long it has been in the fridge.
- Experiment with ratios. Once you have a baseline you like, adjust the coffee-to-water ratio in small increments to dial in your preferred strength.
Start With the Right Beans
Cold brew rewards good coffee more than almost any other method. Because the process is slow and gentle, there is nothing to mask a poor-quality bean — but an excellent bean, brewed cold, shows a side of itself that hot brewing sometimes obscures.
Our coffees are roasted fresh in Melbourne and sourced directly from Indonesian growing regions. They are available whole bean, ready to grind at home, and suited to the cold brew method specifically.
Shop the Single Origin collection and try one for your next cold brew batch. If you have questions about which variety to start with, reach out — we are happy to help you choose.