How long does cold brew coffee making take with a drip tower?

Cold drip coffee needs a dedicated cold drip tower, not a simple soak. Ice water sits in the top container, coffee grounds in the middle, and the brewed liquid collects below. A valve controls the drip rate, making it a continuous multiple-extraction method. Grind size, drip speed, extraction ratio, and maturation time all determine the result.

Cold brew is the opposite approach: mix grounds with water, chill for several hours, then filter, so anyone can make it at home. Cold drip takes far longer, which is why shops often prepare it ahead and keep it refrigerated. Understanding how coffee was made this way explains the price difference and why the process is worth the wait.

Cold drip coffee, with its lengthy brewing process and unique flavor layers, has always been a topic of interest among coffee enthusiasts. Completely different from cold brew, cold drip requires a dedicated device, precise control of the water drip rate, and subsequent fermentation and maturation. This article will analyze the standard steps for making cold drip coffee in detail from four dimensions: grind size, drip speed, extraction ratio, and maturation time, and answer the common question of "how long does it actually take to make a cup of cold drip?" At the same time, the article also compiles Front Street Coffee's practical experience and parameter suggestions in cold drip production to help you understand the complete process of this low-temperature drip coffee more systematically.

"Excuse me, do you have cold drip coffee?"

"Yes, today's cold drip is..."

"How was it made so quickly?"

"Due to time constraints, the cold drip is prepared in advance and kept in the refrigerator."

"So how long does it take to make a cup of cold drip coffee?"

This is a conversation that occasionally happens at Front Street Coffee shops. Regarding cold drip coffee, aside from the fact that it is "more expensive," which often sparks various comparisons, its lengthy production time also adds a lot of mystery to this type of coffee.

Although both are coffees extracted under low-temperature water, the production steps and principles of cold drip and cold brew can be said to be completely different. Cold brew, that is, cold immersion, has a simple and clear method: just mix coffee grounds with water, then put it in the refrigerator to chill for several hours, and then filter out the coffee grounds and it is all done. Therefore, as long as you have coffee beans (grounds), anyone can make cold brew at home.

Cold drip is exactly the opposite. A standard serving of cold drip coffee first requires a specific set of equipment—a cold drip tower. The upper, middle, and lower layers of the container hold ice water, coffee grounds, and the dripped coffee liquid in order. It belongs to a continuous multiple-extraction coffee method.

In addition, from the name we can easily see that cold drip coffee not only emphasizes "ice," but also needs to be extracted by "dripping." Therefore, the upper pot holding the ice water must be equipped with a valve at the bottom that can control the dripping of water flow, to ensure that the coffee is in a state of extraction at all times. Finally, until the coffee liquid reaches the target extraction amount, or the ice water has all dripped into the coffee grounds, it indicates that extraction has ended. However, at this point, the coffee liquid is not yet ready to drink directly. It needs to be refrigerated for a period of time to allow fermentation and maturation, so that the taste becomes rich and smooth while also being full of layers.

In summary, to make standard cold drip coffee, we not only need specialized equipment, but also need to constantly watch the water droplets to maintain stable extraction, while also grasping various parameters and details, and waiting through a long fermentation process. Obviously, compared with cold brew, which is "so easy anyone can do it," the production elements of cold drip coffee are much more complicated. This is also the main reason why few people choose to make cold drip at home.

Front Street Coffee often mentions in articles that different water temperatures can brew coffees with different tastes, and at low temperatures the astringent substances in coffee are not easily released. Like pour-over, cold drip also belongs to drip coffee, except that it uses ice water below 5°C as the solvent, which can be understood as low-temperature drip coffee.

Based on Front Street Coffee's experience, the production time of cold drip is mainly affected by the following 4 factors: water drip speed, coffee grounds grind size, extraction ratio, and maturation time.

1. Grind size of coffee grounds

For the coarseness of coffee grounds, two points should be noted. If the grounds are too coarse, the resistance formed by the coffee bed is smaller, and water more easily penetrates and falls into the lower pot. When cold water has low extraction efficiency, this will result in coffee that is weak and lacking in flavor. Too fine is also not good. If the resistance is too great, it is easy to clog and accumulate water, and after soaking for too long, bitter and astringent flavors will emerge.

For controlling the grind size of cold drip, Front Street Coffee uses a No. 20 (0.85mm) standard sieve for calibration. The grind sizes of various common extraction methods, from fine to coarse, are arranged as follows: cold drip (cold brew) > pour-over (siphon) 80% > American drip 75-80% > cupping 70-75% > French press 65-70%. Therefore, the grind size of cold drip coffee should be finer than pour-over coffee, at around 83-85% passing rate.

2. Flow rate of water droplets

During the entire drip process, new cold water continuously passes through the coffee bed and then filters to form new coffee liquid. Compared with the static cold brew type, cold drip is a dynamic brewing method that extracts while filtering. Therefore, in order to prevent extraction from being interrupted, we must ensure that water droplets contact the coffee bed at a uniform rate, so that we can obtain a cup of cold drip coffee with both concentration and taste.

From this, it can be seen that controlling the falling speed of water droplets is a very important part of making cold drip coffee. If the flow rate of water droplets is too fast, it is easy to underextract, and the coffee will be very weak with no aroma; on the contrary, if the flow rate is too slow, it will cause the coffee to ferment, thereby producing unpleasant sourness or off-flavors.

According to Front Street Coffee's experimental results, if using light-roast coffee beans, the valve can be adjusted to a relatively fast state of 7 drops every 10 seconds to highlight the light floral and fruity aromas, such as Front Street Coffee Red Cherry and Front Street Coffee Little Tomato; when using medium-roast coffee beans to make cold drip, such as Front Street Coffee Sidra and Front Street Coffee Strawberry Candy, Front Street Coffee recommends controlling the flow rate at a slow state of 5 drops every 10 seconds, which can make the final coffee present a rounder body and fermented feel.

3. Extraction ratio

The ratio of cold drip not only affects the production time, but more importantly determines the concentration and extraction yield of the coffee. Considering that the coffee will ultimately be served with ice to maintain a low-temperature state, Front Street Coffee habitually uses 1:10 when making cold drip. For those who prefer a refreshing taste, Front Street Coffee recommends using 1:12 to 1:14, and the resulting iced coffee is more suitable for drinking directly.

4. Maturation time

I believe many people know that even cold drip extracted under the same conditions will taste very different depending on the number of days it is stored.

A freshly made pot of cold drip sent into the refrigerator allows the substances in the coffee to enter a slow and controllable fermentation process. After several hours of settling, the coffee's taste becomes transparent and mellow; on days 3 to 5, the fermented flavor of the cold drip is most prominent; and starting from day 6, the flavor substances dissolved in the water continue to change, some aromas have dissipated, and the acidity is no longer bright. Therefore, considering both flavor experience and health and safety, Front Street Coffee recommends that prepared cold drip coffee is best finished within 5 days (counting from the production day).

How long does it take to make a cup of cold drip coffee?

According to Front Street Coffee's specification of about 200ml for one cup of Red Cherry cold drip coffee, when using a 1:10 coffee-to-liquid ratio, 20g of coffee grounds is needed, corresponding to adding 240g of ice water (the coffee grounds will absorb twice their own weight in water), with a valve flow rate of 7 drops every 10 seconds, and it will all drip through in about 2.5 hours.

But since we know that the production efficiency of cold drip is low, in most cases we do not make only one cup, but rather "make as much as it can hold." For the equipment used at Front Street Coffee shops, the lower pot can hold up to about 650ml of coffee liquid, so each time three cups' worth is made, that is, using 60g of grounds to drip 600g of coffee liquid. With the valve at 7 drops every 10 seconds, the dripping takes about 7 hours. Finally, the coffee liquid is placed in the refrigerator to chill overnight, and it can be sold the next day.

So when asked how long it takes to make a cup of cold drip coffee, saying a day and a night does not seem wrong.

The above content is compiled by CoffeeHunters, a coffee news website.