Water Quality and Coffee Brewing: Why Your Water Matters

A cup of brewed coffee is approximately 98% water. Despite this overwhelming proportion, water quality is often the most overlooked variable in home brewing. You might have the freshest beans, a precision grinder, and perfect technique, but if your water isn't right, your coffee will never reach its potential. Understanding water's role in extraction opens the door to dramatically better coffee.

How Water Affects Extraction

Coffee brewing is fundamentally a process of dissolving soluble compounds from ground coffee into water. The minerals and chemical composition of your water directly influence this extraction process in several ways:

Mineral Content: Minerals in water, particularly magnesium and calcium, act as binding agents that help extract flavour compounds from coffee. Too few minerals (as in distilled water) result in flat, under-extracted coffee. Too many minerals overwhelm extraction and can impart unpleasant tastes.

Bicarbonate Levels: Bicarbonates act as buffers, affecting the perceived acidity of coffee. High bicarbonate levels can mute bright, acidic notes that make specialty coffee vibrant. Low levels may allow excessive sourness.

Chlorine and Chloramines: Municipal water treatment introduces chlorine or chloramines to kill bacteria. These compounds create off-flavours in coffee, often described as "swimming pool" notes. They must be removed before brewing.

Common Water Problems in Australia

Australian tap water quality varies significantly by region. Understanding your local water helps you identify solutions:

Hard Water Regions

Many parts of South Australia, Queensland, and regional areas have hard water with high mineral content. Hard water can cause scale buildup in espresso machines and kettles while producing dull, heavy-tasting coffee. If you notice white deposits on your kettle, you likely have hard water.

Soft Water Regions

Melbourne is known for some of Australia's softest tap water, sourced from mountain catchments. While soft water is gentle on equipment, very soft water may lack the minerals needed for optimal extraction, resulting in sour or flat coffee.

Chlorine Treatment

All Australian municipal water contains some form of chlorine treatment. While safe to drink, these compounds negatively affect coffee flavour. Even low concentrations are detectable in brewed coffee.

Practical Solutions for Home Brewers

Activated Carbon Filtration

The simplest solution for most Australian home brewers is activated carbon filtration through a jug filter (like Brita) or an under-sink system. Activated carbon effectively removes chlorine and chloramines while leaving beneficial minerals largely intact.

For most tap water, a quality carbon filter is sufficient to produce excellent coffee. Change filters according to manufacturer recommendations to maintain effectiveness.

Third Wave Water and Mineral Additives

For those with very soft or very hard water, mineral additives like Third Wave Water offer a precise solution. You add mineral sachets to distilled or reverse osmosis water to create water optimised for coffee brewing. While more effort than filtration, this approach gives you complete control over water chemistry.

Bottled Water

In a pinch, certain bottled waters work well for coffee. Look for mineral water with TDS between 100-150 ppm. Avoid distilled water (no minerals) and heavily mineralised waters (high TDS). Australian brands like Mount Franklin or Pump generally fall in acceptable ranges.

Water Temperature Matters Too

Beyond composition, water temperature significantly affects extraction. The Specialty Coffee Association recommends brewing between 92-96°C for most methods. Here's why temperature matters:

Too Hot (above 96°C): Water that's too hot extracts bitter compounds too quickly, resulting in harsh, astringent coffee. This is particularly problematic with dark roasts.

Too Cool (below 90°C): Insufficient heat leads to under-extraction, producing sour, weak coffee lacking body and sweetness. Light roasts are especially sensitive to low temperatures.

For pour-over and French press, boil your kettle and let it sit for 30-60 seconds before brewing. Many electric gooseneck kettles now offer precise temperature control, a worthwhile investment for serious home brewers.

Equipment Considerations

Water quality affects not just flavour but also equipment longevity:

Scale Buildup

Hard water causes calcium carbonate scale to accumulate inside kettles, boilers, and heating elements. Scale reduces heating efficiency, can block water flow in espresso machines, and eventually causes equipment failure. Regular descaling with citric acid or commercial descalers extends equipment life.

Espresso Machine Protection

Espresso machines are particularly sensitive to water quality. Many manufacturers void warranties if scale damage results from poor water. If you own an espresso machine, invest in proper filtration or water treatment as preventive maintenance.

Simple Steps to Better Water

You don't need to become a water chemist to improve your coffee. These practical steps will benefit most home brewers:

• Start with a carbon filter jug or tap attachment to remove chlorine
• If your water tastes metallic, excessively hard, or noticeably off, consider bottled water or mineral additives
• Use water at the right temperature (92-96°C for most methods)
• Descale your equipment regularly if you have hard water
• Taste your water plain; if it tastes bad, it won't make good coffee

Water might not be the most exciting topic in coffee, but optimising it is one of the simplest ways to improve your daily cup. A small investment in filtration pays dividends every time you brew.