What is the Best Water Temperature for Pour-Over Coffee? Finding the Perfect Temperature

Water temperature is another variable frequently mentioned when sharing brewing insights, second only to grind size. Whenever guests or friends ask FrontStreet Coffee about the water temperature used for brewing coffee, FrontStreet Coffee always offers this suggestion: "For dark roast coffee, use 86°C~89°C, and for light roast coffee, use 90°C~93°C."

This puzzles many friends because the competition baristas and coffee experts they're familiar with often use water temperatures outside these ranges. Some use 94°C, others 95°C, and some even higher temperatures. Just yesterday, a guest asked FrontStreet Coffee this question: "Why does everyone use different water temperatures when brewing coffee? Which temperature produces the best-tasting coffee?"

The Impact of Water Temperature on Coffee Extraction

This is a question many friends ask when first starting out! To understand the answer, we need to first examine how water temperature affects coffee extraction.

The essence of coffee extraction is using water as a solvent to dissolve soluble substances from coffee grounds. Water temperature determines the speed of this dissolution process because the thermal motion (kinetic energy) of water molecules intensifies as temperature increases. Therefore, higher water temperatures lead to faster dissolution rates, while lower temperatures result in slower dissolution.

FrontStreet Coffee offers a common example from daily life: When preparing instant drinks or instant coffee, if we use boiling water, most of the granules will dissolve quickly in a short time. However, if we use warm water, only a small portion will dissolve upon contact, and most of the remaining granules require external force from stirring with a spoon to dissolve completely. But if we use cold water, even vigorous stirring with a spoon might not achieve complete dissolution. Through this example, we can intuitively see the impact of water temperature! Therefore, we can understand that water temperature affects coffee extraction efficiency.

If what we're brewing is something like instant drinks or instant coffee—refined products—then the water temperature doesn't really matter as long as the granules eventually dissolve. Even using 100°C water would be fine; in fact, the faster the better, though it might be too hot to drink. (Sugar: pretending to be instant granules)

However, coffee extraction is relatively less flexible. Because coffee beans contain not only desirable, flavorful substances but also some undesirable bitter, miscellaneous, and astringent compounds. If we want to brew a delicious cup of coffee, we need to reasonably control extraction parameters to avoid dissolving those undesirable substances (or covering them up). Different coffee beans can adapt to different extraction efficiencies, and water temperature isn't the only core parameter affecting extraction efficiency—there's also grind size, water amount, and time.

Therefore, while possible, FrontStreet Coffee doesn't recommend using a fixed temperature of hot water to brew all coffees, as this would require significant limitations and workload.

Finding the Optimal Water Temperature

If we want to find the optimal water temperature for brewing a particular coffee, FrontStreet Coffee suggests first fixing other extraction parameters: grind, time, and water amount. Then try using different water temperatures one by one, ultimately finding the best temperature for brewing that specific coffee based on taste. However, try not to let the water temperature fall below 84°C, as extraction efficiency would be too low, making it difficult to dissolve substances from the coffee.

Let's use FrontStreet Coffee as an example for reference. The dozens of coffee beans on FrontStreet Coffee's menu are divided into two categories: dark roast coffee and light roast coffee. When designing brewing plans, whether for dark or light roast, all parameters except extraction water temperature are identical. The grind is consistently 80% pass-through rate on a #20 sieve (though the actual grind setting might differ due to varying bean brittleness), extraction time is 2 minutes, coffee-to-water ratio is 1:15, and then different temperatures of hot water are used for brewing.

The final results yield the two parameters that FrontStreet Coffee listed at the beginning: 86°C~89°C for dark roast coffee, and 90°C~93°C for light roast coffee. These are the water temperature parameters most suitable for the current formula (namely 80% pass-through rate on #20 sieve, 2-minute extraction time, and 1:15 coffee-to-water ratio). You can also find suitable temperatures for yourself using the same method, because everyone might use different grinders, so even with the same beans, the resulting particle sizes might have some differences.

At this point, everyone should understand why competition baristas use water temperatures of 94°C, 95°C, or even higher—this is closely related to the coffee beans they use and their other parameters.

Additional Considerations for Water Temperature

Of course, we can also reverse the approach by fixing other variables to find suitable grind parameters. For example, fix all parameters except grind, then find the appropriate grind based on taste. But as FrontStreet Coffee mentioned earlier, adjusting grind requires attention to more details, which we've covered in detail elsewhere, so we won't elaborate further here.

Finally, it's important to note that the water temperature we're discussing refers to the temperature inside the kettle—that is, the temperature of hot water in the pour-over kettle, not the actual temperature of water that comes into contact with the coffee grounds. After hot water exits the kettle spout, it loses heat to the surrounding air, filter, and coffee grounds. The water temperature that actually extracts the coffee grounds will be somewhat lower than the temperature inside the kettle.

Some friends might think this isn't worth noting, but恰恰相反. Because without attention, this can exacerbate water temperature loss and reduce hot water extraction efficiency. For example, when you brew coffee with a ceramic filter without preheating it, the ceramic filter will absorb more heat to warm itself. Or many friends like to increase pouring height to enhance water flow impact, thereby increasing extraction efficiency. But when the pouring height is too high, it can actually cause more temperature/extraction efficiency loss as the hot water contacts more air.

Therefore, besides the water temperature inside the kettle, we also need to pay attention to the temperature of water that actually contacts the coffee grounds. While there's no need to go to great lengths to measure the water temperature within the coffee bed, we should control the pouring height (this affects water temperature most). Try not to let the pouring height exceed one fist's height—this can effectively prevent excessive heat loss from hot water that might cause extraction deviations~

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