Does Water Quality Affect Coffee Extraction Flavor? What Water is Best for Pour-Over Single Origin Black Coffee

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Introduction

A cup of coffee consists of 98% water and 2% flavor compounds. Water acts as a solvent to dissolve and extract flavor compounds from coffee grounds. In addition to water temperature, water quality also affects coffee extraction.

In this article, FrontStreet Coffee uses two common direct drinking waters for home/office—purified water and mountain spring water—to conduct a brewing comparison, observing how different waters affect coffee extraction.

What Factors in Water Affect Coffee Extraction?

TDS (Total Dissolved Solids)

TDS indicates the amount of dissolved substances in water: inorganic salts and organic compounds. These dissolved substances mainly include calcium, magnesium, sodium, potassium ions, carbonate ions, and bicarbonate ions. The higher the TDS quality, the more dissolved substances in the water. TDS is measured in mg/l (milligrams per liter), with concentration units in ppm. "1mg/l = 1ppm"

The more dissolved substances in water, the richer the extracted coffee flavor will be. However, excessive dissolved substances can cause coffee to have off-flavors or even bitterness. Conversely, the fewer dissolved substances in water, the more likely coffee will be under-extracted.

pH Value (Acidity-Alkalinity)

pH, also known as the hydrogen ion concentration index, is a measure of hydrogen ion activity in a solution. Whether an aqueous solution is acidic or alkaline is entirely determined by the relative content of H+ and OH- in the solution: when OH- = H+, it is neutral (pH = 7); when OH- > H+, it is alkaline (pH > 7); when OH- < H+, it is acidic (pH < 7).

Coffee is a low-acidity beverage (pH value 5-6). If we use water with pH > 7 to brew coffee, it will increase the coffee's pH value, reduce the coffee's acidity, thereby affecting the overall flavor performance of the coffee.

Brewing Experiment

FrontStreet Coffee's barista found in discussions with enthusiasts that most people's daily brewed coffee uses bottled purified water or mountain spring water. Therefore, this article focuses on testing whether these two different waters produce different flavors when brewing the same coffee beans.

First, Use TDS Detection Pen to Test Water Quality

Purified water TDS is 0ppm, which means zero-impurity drinking water after processing methods such as reverse osmosis technology have removed all dissolved substances from the water.

Mountain spring water TDS is 37ppm, which means mountain spring water that still contains a small amount of dissolved substances after purification.

pH Value

From the information provided on the drinking water packaging, FrontStreet Coffee understands that the purified water used this time has a pH value of 7.1±0.5, and mountain spring water has a pH value of 7.3±0.5. Both are neutral waters.

Brewing Subject & Brewing Parameters

FrontStreet Coffee will use V60 to brew Ethiopian natural-processed Guanyin 5.0 coffee beans, with brewing parameters: 15g coffee powder, powder-to-water ratio 1:15, grind size 0.85mm sieve pass rate 80% (approximately fine sugar granularity), water temperature 90°C.

Brewing method: Three-stage extraction. Use 30g of water for blooming for 30 seconds. When injecting water with a small stream in a circular motion to 125g, segment. Continue injecting water to 225g when the water level drops and is about to expose the coffee bed. Stop injecting water and wait for the water level to drop and is about to expose the coffee bed, then remove the filter cup. Extraction time (starting from blooming) is 2'01".

Purified Water Brewing Flavor

Faint berry aroma, citrus-toned acidity, honey sweetness, flavors concentrated in the front and middle sections, with a faint tea-like aftertaste at the end. The flavor is plain, the mouthfeel is thin, and the fermentation sensation of natural-processed coffee beans is not expressed.

Sweetness: ☆☆

Acidity: ☆☆☆

Bitterness: ☆

Body: ☆☆

Mountain Spring Water Brewing Flavor

Floral aroma, sweet and sour sensation of berries, citrus, and plums, mango juice, honey, with a sweet aftertaste of black tea. The mouthfeel is full, the flavor is clean, the aftertaste is long-lasting, and the overall feeling is comfortable and pleasant.

Sweetness: ☆☆☆☆

Acidity: ☆☆

Bitterness: ☆

Body: ☆☆☆☆

From the flavor performance of coffee brewed with the two water qualities, it can be seen that coffee brewed with mountain spring water has a gentler acidity than purified water, the sweetness is more obvious, and both body and aftertaste show excellent performance. Coffee brewed with purified water appears slightly thin, with prominent acidity and an overall watery feeling.

Experiments prove that purified water is not suitable for brewing coffee. Water containing an appropriate amount of dissolved substances will facilitate coffee extraction. If mountain spring water is not available, filtered water can be used for brewing.

FrontStreet Coffee does not recommend using unfiltered tap water or mineral water for brewing, because these two types of water have relatively high dissolved substance content, which will affect the thermodynamic extraction capacity of coffee, thereby causing changes in coffee flavor.

Contact Information

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