Water & Filtration

Water is coffee's hidden ingredient, comprising 98% of your brew. Understanding water chemistry—alkalinity, hardness, and filtration—unlocks consistent extraction and exceptional flavor in every cup.

Water Chemistry Fundamentals

Water alkalinity testing kit and results

Alkalinity: The Acidity Buffer

Alkalinity measures water's ability to resist pH changes and is primarily driven by bicarbonate. It acts as a buffer that suppresses sourness in coffee, making it the most influential factor in perceived acidity.

40ppm
Target for Filter Coffee
20-30ppm
For Espresso
Buffer
Primary Role
High Alkalinity: Flattened acidity, muted flavors
Low Alkalinity: Bright, sharp, potentially sour
Target Range: Balanced brightness and clarity
Alkalinity Guide →
Water hardness from calcium and magnesium ions

Hardness: Extraction Power

Hardness measures calcium and magnesium ions that drive extraction by interacting with coffee solids. It provides the "power" for flavor extraction while contributing to body and mouthfeel.

17-85ppm
Preferred Range
Ca & Mg
Primary Ions
GH
Measurement
Low Hardness: Thin, bright, under-extracted
Optimal Hardness: Balanced extraction with body
High Hardness: Over-extraction, bitterness
Hardness Guide →
Water pH testing for coffee brewing

pH: The Secondary Player

pH indicates current acidity/alkalinity but has less impact on coffee taste than alkalinity when near neutral. Water can have high alkalinity with neutral pH, creating strong buffering without appearing alkaline.

6.5-7.5
Acceptable Range
7.0
Neutral pH
Secondary
Importance
Near Neutral (6.5-7.5): Acceptable for coffee brewing
Alkalinity Matters More: Controls perceived acidity
Use as Diagnostic: Check alongside alkalinity
pH Guide →

TDS & Measurement Tools

Refractometer measuring coffee TDS

Understanding TDS

Total Dissolved Solids measures the concentration of extracted coffee compounds. It's a result variable that indicates extraction success, not a control parameter like alkalinity or hardness.

Pour-over: 1.2-1.7% TDS
Espresso: 8-12%+ TDS
Cupping: 1.2-1.5% TDS
TDS Guide →
Water testing kit for alkalinity and hardness

Essential Testing Equipment

Accurate water management requires reliable testing tools. Drop-count titration kits provide precise alkalinity and hardness measurements, while refractometers measure brewed coffee TDS and extraction yield.

Drop-Count Kit: Alkalinity & hardness testing
Refractometer: Coffee TDS & extraction yield
pH Meter: Water pH measurement
Testing Guide →

Water Filtration Methods

Activated carbon water filter pitcher

Activated Carbon Filtration

Activated carbon filters remove chlorine, odors, and organic compounds that affect taste. They're ideal for improving municipal water flavor without significantly altering mineral content.

Removes: Chlorine, odors, organics
Preserves: Natural minerals
Cost: Low maintenance
Best for:

Acceptable tap water that needs flavor improvement

Carbon Filtration Guide →
Reverse osmosis water filtration system

Reverse Osmosis (RO)

RO removes 95-97% of dissolved solids, creating a clean slate for precise mineral control. When combined with blending, RO provides the ultimate control over water chemistry for coffee.

Removes: 95-97% of TDS
Control: Precise mineral dosing
Best for: Hard water areas
Step 1: RO removes minerals
Step 2: Add targeted minerals
Step 3: Blend for target profile
RO Guide →
Water softener with ion exchange resin

Ion Exchange Systems

Ion exchange systems replace calcium and magnesium with sodium, reducing scale but degrading coffee extraction quality. Not recommended for coffee applications despite scale reduction benefits.

Warning: Not suitable for coffee
Problem: Replaces Ca/Mg with Na
Result: Poor extraction quality
Better Alternative:

RO + remineralization for scale control without sodium addition

Ion Exchange Guide →

DIY Water Recipes

DIY coffee water recipe ingredients and setup

Two-Bottle Concentrate Method

Create precise water chemistry using sodium bicarbonate (buffer) and magnesium sulfate (hardness). This method provides precise control over alkalinity and hardness for consistent brewing results.

Buffer Solution: 1.68g NaHCO3 per 1L DI water
Hardness Solution: 2.45g MgSO4·7H2O per 1L DI water
Target Mixing: Add ml of each to reach desired KH/GH
DIY Recipes →
Coffee water recipe targets and SCA guidelines

Popular Recipe Targets

Industry-standard recipes like SCA, Rao, and Barista Hustle provide proven starting points for different brew methods and flavor profiles. These recipes balance alkalinity and hardness for optimal extraction.

SCA Profile: 40ppm KH / 68.6ppm GH
Rao Profile: 50.1ppm KH / 75.7ppm GH
Barista Hustle: 40ppm KH / 80.7ppm GH
Espresso: Lower alkalinity per gram of coffee
Filter: Higher alkalinity for clarity
Recipe Guide →

Water for Different Brewing Methods

Espresso Water Adjustments

Espresso's low beverage ratio concentrates the effect of water chemistry per gram of coffee. Lower alkalinity helps preserve acidity and prevents excessive buffering in concentrated extractions.

Alkalinity: 20-30 ppm (lower than filter)
Hardness: 50-100 ppm (balanced extraction)
Consideration: Scale risk from concentrated use

Key Adjustments:

  • Lower alkalinity to preserve acidity
  • Monitor hardness for extraction power
  • Consider descaling frequency
  • Some calcium for boiler protection
Espresso Water Guide →

Filter Coffee Water

Filter brewing benefits from moderate alkalinity to achieve clarity and balance without muting origin characteristics. The longer contact time and higher ratios allow for different chemistry targets.

Alkalinity: 30-50 ppm (balanced brightness)
Hardness: 30-80 ppm (good extraction)
Focus: Origin expression and clarity

Optimization Tips:

  • Higher alkalinity for brighter profiles
  • Lower hardness for cleaner cups
  • Consider origin characteristics
  • Adjust for roast level
Filter Water Guide →

Water-Related Troubleshooting

Common Water Problems & Solutions

Most coffee taste issues can be traced back to water chemistry imbalances. Understanding the relationship between taste symptoms and water parameters enables quick diagnosis and correction.

Flat, Muted Coffee:

Cause: High alkalinity buffer

Solution: Lower alkalinity to 30-40ppm

Sour, Sharp Taste:

Cause: Low alkalinity

Solution: Raise alkalinity to 40ppm

Bitter, Muddy:

Cause: High hardness

Solution: Reduce hardness or increase alkalinity

Rapid Scale Buildup:

Cause: High temporary hardness

Solution: Filtration or RO blending

Full Troubleshooting →

Equipment Protection & Longevity

Espresso machine with limescale buildup

Managing Scale & Corrosion

Water mineral content directly affects equipment longevity. Understanding temporary vs. permanent hardness helps you choose the right filtration strategy to protect your investment.

Temporary Hardness: Forms scale when heated
Permanent Hardness: Doesn't form scale
LSI Monitoring: Calculates scale tendency
Scale Prevention:

Filtration, proper chemistry, regular descaling

Corrosion Protection:

Maintain some calcium, avoid aggressive chemistry

Equipment Protection →

Perfect Your Water

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