手沖中濾杯水的濃度階梯續篇：同樣參數下，高低水位為什麼沖出兩種結果？The Concentration Gradient Inside the Dripper (Part II): Why Different Water Levels Yield Different Results Under the Same Parameters
目錄:
1. 實驗分析：相似的 TDS，截然不同的風味世界
2. 不同水位 咖啡口感差很多
3. 手沖關鍵：濾杯水的濃度階梯
上一篇提到，手沖時真正一直在變的，不只是咖啡粉，還有濾杯裡那層水的狀態。熱水一旦接觸咖啡粉，就會開始帶走香氣、酸、甜與其他可溶性物質，因此濾杯中的水，不再只是單純的熱水，而是一層會逐步累積咖啡成分、並慢慢改變溶解力的水。這也就是上一篇所說的：手沖中濾杯水的濃度階梯。
這次，我們用同一支豆子做了高低水位實驗。豆子是 哥斯大黎加 塔拉珠 聖伊西德羅莊園 El Cedro地塊 藝妓 紅蜜處理，風味表現本身就很有層次，帶有茉莉花、雞蛋花、蜜蘋果、柑橘、桃子、蜂蜜，尾韻是花蜜般的香甜綿密感。這類型的豆子，理論上如果萃取得當，會有很漂亮的花香上揚、明亮柑橘酸質，以及柔和卻有支撐的甜感；但如果萃取不均，原本細緻的花果調也很容易被酸澀感與空薄感蓋掉。也正因如此，它很適合拿來觀察高低水位對風味結構的差異。
In the previous article, we discussed how the coffee grounds aren't the only thing changing during a pour-over, the state of the water layer in the dripper is also in constant flux. Once hot water touches the grounds, it begins carrying away aromatics, acids, sugars, and other solubles. Consequently, the water in the dripper is no longer just "pure" water; it becomes a layer that gradually accumulates coffee components and loses its dissolving power. This is what we call the Concentration Gradient in the previous article.
This time, we conducted an experiment using the same beans to compare high and low water levels. We used a Costa Rica Tarrazú San Isidro Estate, El Cedro Plot, Geisha Red Honey Process coffee bean. This coffee is naturally complex, featuring notes of jasmine, frangipani, honey crisp apple, citrus, peach, and honey, with a sweet, syrupy nectar-like finish. Theoretically, if extracted properly, this bean offers beautiful floral aromatics, bright citrics acidity, and a soft yet structured sweetness. However, if the extraction is uneven, the delicate floral and fruity tones can easily be overshadowed by astringency or a "hollow" mouthfeel. This makes it a perfect candidate for observing how water level affects flavor structure.
實驗分析：相似的 TDS，截然不同的風味世界
這次兩組手沖，參數完全相同：15克粉、225克水。
分段注水重量為 37 / 100 / 160 / 225克，分段時間為 00:40 / 1:05 / 1:40 / 2:40。也就是說，粉量一樣、水量一樣、分段節奏一樣、總時間也一樣，唯一改變的是手沖時濾杯中維持的水位高低，以細水注及粗水注來改變水位低高。
第一組是低水位手沖
最後咖啡液量為 170克，TDS 1.26。風味表現上，熱的時候首先感受到的是酸澀與萃取不均，主調偏向佛手柑、檸檬皮。這代表這杯不是沒有香氣，也不是沒有柑橘調，而是前段被拉得比較尖，柑橘表現偏向外皮感，而不是成熟果汁感。隨著降溫，柑橘調還在，但整體開始出現一種空的感覺，也就是風味有輪廓，卻少了中段支撐與甜感包覆。到了低溫時，花香與佛手柑依然能辨識出來，但整體結構偏薄，少了這支紅蜜藝妓原本應有的蜂蜜感與花蜜尾韻。
第二組是高水位手沖
最後咖啡液量為 181克，TDS 1.24。雖然濃度數值比低水位那杯還略低一點，但喝起來卻明顯更完整。熱的時候是酸質明亮、甜感強，除了佛手柑那種清楚的柑橘調，更出現了花蜜、紅玉茶甜這類更圓潤、更成熟的甜感。降溫之後，風味轉為佛手柑、紅茶、溫潤，低溫時則留下柔和的柑橘酸。整杯喝起來不像低水位那樣有尖銳的酸澀感，反而更接近這支豆子本身應有的表現：花香有撐起來，甜感有延續，尾韻也更綿密。
這組實驗最值得注意的地方，就是：兩杯TDS非常接近，但風味差很多。低水位是 1.26，高水位是 1.24，若只看濃度，很容易以為兩杯差異不大；但實際喝起來，一杯偏酸澀、偏空、帶有萃取不均感，另一杯卻是酸明亮、甜感強、尾韻更完整。這再次說明，手沖不是只看最後杯中溶解了多少，而是要看這些物質是如何被溶解出來的。
For both brews, the parameters were identical:
Coffee: 15g
Total Water: 225g
Pour Intervals: 37g / 100g / 160g / 225g
Timing: 00:40 / 1:05 / 1:40 / 2:40 (Total Time)
Everything—dose, yield, rhythm, and time—stayed the same. The only variable was the water level maintained in the dripper, which was controlled by using a narrow stream (low level) versus a heavy stream (high level).
Group 1: Low Water Level
Yield: 170g | TDS: 1.26
The flavor profile in hot stage shows the initial notes of sourness, astringency, and uneven extraction. The main profile leaned toward bergamot and lemon peel. This doesn't mean the coffee lacked aroma or citrus, but rather that the "brightness" was pulled too sharply, resembling citrus zest rather than ripe juice. As it cooled, the citrus remained, but the body became hollow, it had a flavor profile but lacked mid-palette support and sweetness. In cold stage, while jasmine and bergamot were still identifiable, the structure was thin, missing the honey-like body and floral nectar finish typical of this Red Honey Geisha.
Group 2: High Water Level
Yield: 181g | TDS: 1.24
Although the TDS value was slightly lower than that of the low-water-level cup, it tasted significantly more complete. When it’s hot, bright acidity with intense sweetness. Beyond the clear bergamot notes, more rounded and mature sweetness emerged, such as floral nectar and Ruby black tea. When it’s cooling down, the profile shifted toward a smooth blend of bergamot, black tea, and warmth. When in cold stage, left behind a soft, lingering citrus acidity. The cup lacked the sharp astringency of the low-level brew; instead, it achieved the bean's true potential: supported florals, sustained sweetness, and a dense, syrupy finish.
The most noteworthy finding is that despite having very similar TDS (1.26 vs. 1.24), the flavor profiles were worlds apart. If we only looked at concentration, we might assume the brews were nearly identical. However, in practice, one was astringent and hollow, while the other was bright acidity, intense sweetness, and complete aftertaste. This proves that pour-over quality isn't just about how much dissolved into the cup, but how those substances were extracted.
為什麼相同參數下，低水位反而比較容易出現這種結果？
因為低水位時，濾杯中的水更新得快，水本身比較接近乾淨狀態，因此理論上溶解力較高。但另一面是，當水位偏低，水柱對粉床局部的影響會更直接，若控制稍微不夠穩定，就更容易讓某些區域被沖得太多、某些區域卻接觸不足。最後就會出現前段物質被快速抓出來，亮度雖然有，但甜感與中段支撐沒有跟上，於是喝起來容易變成檸檬皮、佛手柑外皮、酸澀感偏明顯，甚至在降溫後顯得空。
相反地，高水位雖然讓濾杯中的水，已經先帶有部分咖啡物質，水本身的「新鮮溶解力」理論上會稍微下降，但它卻提供了更穩定的萃取環境。當濾杯中保有較高水位時，水柱先進入上方那層水，再比較平均地穿過粉床，整體受水更連續，也更不容易發生局部短路與旁通。因此，即使TDS沒有更高，風味卻更容易把花香、果酸與甜感接在一起，讓這支 El Cedro 藝妓紅蜜該有的茉莉花、蜜蘋果、桃子、蜂蜜與花蜜尾韻，更完整地呈現出來。
Why does the low water level tend to produce these results?
At a low water level, the water in the dripper is refreshed quickly and remains closer to a "pure" state, which theoretically means higher solvent power. However, the downside is that the water stream has a more direct and aggressive impact on the coffee bed. If the pour isn't perfectly stable, it is easier to over-extract certain areas while under-extracting others. As a result, the front-end compounds are extracted too rapidly; while there is plenty of brightness, the sweetness and mid-palette support fail to keep pace. Consequently, the flavor profile tends toward lemon zest or bergamot peel, with a more pronounced sourness and astringency that can even feel hollow once the coffee cools.
Conversely, while the water in a high-level brew already carries some coffee solids (reducing its "fresh" solvent power), it provides a much more stable extraction environment. The incoming stream hits the existing water layer first, allowing the water to pass through the coffee bed more uniformly. This minimizes short-circuiting and bypass. Therefore, even without a higher TDS, the flavor profile more effectively bridges the florals, fruit acidity, and sweetness. This allows the jasmine, honey apple, peach, honey, and the characteristic nectar-like finish of this El Cedro Geisha Red Honey to be presented more completely.
手沖關鍵：濾杯水的濃度階梯
這次實驗讓我們更確定一件事：
低水位不一定比較厲害，高水位也不只是稀釋。
低水位的優勢，是單位水的溶解力較強；高水位的優勢，則是整體粉床更穩、萃取更均勻。對於像這支哥斯大黎加塔拉珠 聖伊西德羅莊園 El Cedro 藝妓紅蜜這種本身花香細緻、甜感要靠結構撐起來的豆子來說，高水位反而更容易把它的完整性沖出來。
所以，當我們在談手沖控制時，不能只看水量與時間，還要看：你讓濾杯裡那層水，長時間維持在什麼狀態。因為真正決定這杯咖啡走向佛手柑檸檬皮的酸澀，還是走向花蜜、紅茶與蜂蜜甜感的關鍵，往往就藏在這道平常最容易忽略的——濾杯水的濃度階梯。
This experiment confirms one thing: A low water level isn't necessarily better, and a high water level isn't just dilution.
Low water level has stronger extraction power per unit of water. High water level has superior bed stability and extraction uniformity. For beans like the Costa Rica San Isidro El Cedro, where delicate florals and sweetness depend on a solid structural balance, a high water level is actually more effective at bringing out the coffee's integrity.
When we discuss pour-over control, we must look beyond volume and time. We must consider the state of the water layer we maintain in the dripper. The difference between a cup that tastes like bitter lemon peel and one that tastes like sweet honey nectar often lies in the most overlooked variable: the Concentration Gradient.
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