Flash Brew Coffee: Master the Art of Iced Coffee

Updated Apr 12, 2024 • Wanjiku Kimari

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Flash brew coffee is one of the lesser-known brewing styles, gaining popularity among specialty coffee lovers nowadays. Unlike traditional iced teas that tend to get diluted, flash brews have rich flavors, resulting in vibrant iced coffee. Plus, it takes a fraction of the time you would spend to prepare a cold brew. Discover why flash brew is an excellent alternative to cold brews and traditional iced coffee varieties. 

What is Flash Brew Coffee? 

Flash brew coffee, or Japanese iced coffee, is a versatile coffee made by pouring hot brewed coffee over ice to cool it rapidly, creating well balanced and nuanced brew. 

One advantage of flash brews is its versatility. One can use pour-over, french press, or any other hot brewed coffee to make a flash brew. It allows you to experiment with the unique flavor profiles of the different brewing methods to your preference. 

Flash brewing originates from traditional Japanese pour-over coffee brewing methods. Japan is one of the world's biggest coffee importers, with a coffee brewing culture that emphasizes precise brewing variables.     

Japanese iced coffee gained popularity in the 1960s when flash brews became a staple in Japanese coffee shops. 

As coffee enthusiasts and baristas explored different brewing methods, sharing techniques and the rise of international coffee competitions over the years have contributed to the uptake of flash brew coffee outside Japan. 

Additionally, social media and online platforms have helped inspire cover lovers worldwide to experiment with flash brewing, contributing to its popularity and adoption as an alternative option for making iced coffee with pronounced flavor and aroma.  

Pouring into a pour-over maker with ice on the bottom

Benefits of Flash Brew Coffee

Flash brew coffee is made by pouring hot water over coffee grounds in a pour-over dripper like the Hario V60. The hot water extracts the flavors as it passes through the coffee and is immediately cooled as it drips onto a layer of ice cubes. 

It is a quick brewing process, hence the name flash brew, resulting in a bright and flavorful coffee. Here are some benefits of flash brew coffee that contribute to its popularity as a refreshing summer beverage:

  1. Speedy Preparation: Unlike cold brews that require hours of steeping, flash brew coffee can be prepared in a matter of minutes, making it a convenient choice for those seeking a quick, refreshing caffeine fix.
  2. Rich Flavor Profile: The use of hot water in flash brewing allows for a more robust extraction of the coffee's flavors, resulting in a cup that is vibrant, nuanced, and less diluted than traditional iced coffee.
  3. Versatility: Flash brew coffee can be made using various brewing methods, including pour-over, French press, and more. This versatility allows coffee enthusiasts to experiment with different flavor profiles and brewing techniques.
  4. Refreshing: The immediate cooling of the coffee preserves its freshness and results in a crisp, clean taste that is perfect for hot summer days.
  5. Lower Acidity: Despite the use of hot water, flash brewing tends to result in coffee with lower acidity than traditional hot brews, making it a gentler option for those with sensitive stomachs.

Brewing Method

Flash brew coffee takes a notably shorter time to prepare than other varieties of iced coffee, such as cold brew. It involves pouring hot water over coffee grounds in a pour-over dripper and letting it drip into a container with ice. 

In comparison, cold brewing requires steeping coffee grounds in cold water for several hours. Conventional iced coffee has a similar brewing process, only that the cooling process takes longer before serving with ice. 

While most people are familiar with the pour-over method for making flash brew coffee, you can use other hot brewing styles like the French press. However, pour-over or drip methods offer the most convenience, especially when brewing a large batch. 

Aeropress and a cup of ice
Aeropress Recipe

Flavor Profile

Flash brew coffee has a short extraction period, resulting in a brew with a more vibrant taste profile. Short brew times extract acidic compounds, giving the coffee brightness and a pleasant tang.  

Additionally, hot water enables the extraction of a wide range of flavors, so you enjoy the nuanced characteristics of the beans. It is one of the reasons why coffee lovers use specialty coffee to make flash brews. 

How to Make Flash Brew Coffee 

Flash brew coffee requires only three ingredients; fresh medium-grind coffee, hot water, and ice. The brewing equipment includes a gooseneck kettle and cone-shaped drippers like Chemex and Hario V60. You may also want to include a thermometer to measure the water temperature, a scale to measure your coffee and a timer. Then, follow the step-by-step process below to prepare your coffee.


  1. The first step is to measure the coffee beans and grind them to a medium-fine consistency. You'll need 16g of coffee for 225 ml of water, translating to a 1:16 brewing ratio
  2. Next, heat the water between 195°F to 205°F using a gooseneck kettle. If you don't have one, put the hot water into a dispenser with a spout for easy pouring.
  3. Organize the pour-over dripper with a cone filter and rinse the filter with some hot water to remove the papery taste.
  4. Place your dripper over your tumbler with about 100g of ice cubes. 
  5. Put the ground coffee in the dripper and set your timer to begin brewing.
  6. Slowly pour a little hot water in a circular motion to wet the grounds. Swirl the dripper to ensure the coffee is saturated, and let it bloom for about 45 seconds. 
  7. After blooming, pour more water and swirl the dripper to agitate the coffee. 
  8. Finally, pour the rest of the hot water slowly and complete the brewing process. Ideally, it should take about two minutes to flash brew your coffee. 
YouTube video embed

Tips for Perfecting Your Flash Brew


Coffee drippers come in three shapes; trapezoid, flat bottom, and cone. The shape affects the flow rate during brewing, thus affecting the flavor of the brewed coffee. Cone-shaped drippers like Hario V60 and Chemex are the best for flash brews as they enable a faster flow rate, giving the flavor and aroma better clarity.

Brewing Ratio

The brewing or coffee ratio refers to the amount of coffee relative to the water you use to brew. Thus, a 1:16 ratio means 16 grams of water for every gram of coffee. Typical ratios vary from 1:15 to 1:18, where 1:15 will produce a more concentrated brew than 1:18. 


When hot water contacts coffee, it rapidly releases carbon dioxide trapped within the grounds. This reaction is called blooming and is necessary when brewing with the pour-over method to prevent the gases from souring the coffee. 


The Flash brew is an alternative variety of iced coffee with a vibrant and more nuanced flavor than conventional iced coffee. It also takes less time to prepare, making it easy to brew at home with everyday equipment. 

While it is not as popular as cold brew, it is beloved among specialty coffee fans. However, as more people became enthusiastic about coffee and different brewing styles, the flash brew could be a summer favorite soon.

Meet the expert

Wanjiku is an experienced interior designer who loves creating beautiful spaces, one room at a time. When not designing, you can find her enjoying her favorite coffee drinks and planning her next road trip adventure!

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