Crystal Clear Brews: Unveiling the Secrets of Water Quality in Coffee

Have you ever wondered why your carefully crafted espresso at home might not taste quite as exquisite as the one from your favourite coffee shop? Or perhaps you've noticed that your tried and tested V60 and regular beans taste different while travelling? If you're a coffee aficionado, it's time to dive into the not-so-secret ingredient that makes up 98% of your beloved brew: water!

Many coffee lovers focus on selecting the perfect beans, dialling in the grind size, and mastering the art of extraction. However, the quality of water used in the brewing process often gets overlooked. It's no small matter, as water plays a starring role in extracting the delightful flavours and aromas from those precious coffee grounds.

It's time to shed some light on the fascinating world of H2O and its impact on coffee. From the mineral content and pH balance to total dissolved solids, water quality can make or break your espresso experience. So, let's embark on a light-hearted journey to unravel the mysteries of water in coffee, and discover how you, the passionate espresso enthusiast, can elevate your brew game by paying attention to the liquid that brings your beans to life!

water quality factors that can influence the quality of your coffee

We'll be looking at the following factors that have an influence over the quality of your coffee, no matter what your brewing technique is;

  • The role of minerals such as magnesium and calcium
  • The Importance of pH and finding the right balance
  • How temperature is the final piece of the puzzle and what factors can influence what the perfect temperature would be

The Role of Magnesium, Calcium, and Bicarbonate in Coffee Extraction

Magnesium, calcium, and bicarbonate are minerals found in water that play a crucial role in coffee extraction. They help dissolve the flavourful compounds from coffee grounds into the water, creating a well-rounded and balanced cup of coffee. The right balance of these minerals is essential to achieve optimal extraction and avoid issues like under-extracted (sour) or over-extracted (bitter) coffee.

Magnesium and calcium ions in water have a positive charge, which allows them to interact with the negatively charged coffee compounds, such as acids, oils, and other flavour molecules. This interaction promotes the dissolution of these compounds into the water, contributing to a more efficient extraction process.

Bicarbonate, on the other hand, acts as a buffer in water, helping to neutralise some of the acidity in coffee. This results in a smoother and more balanced flavour profile. However, too much bicarbonate can lead to an overly flat taste or even hinder the extraction of certain compounds.

Think of these minerals as dance partners for the coffee solubles. Magnesium and calcium ions gracefully interact with the coffee compounds, encouraging them to join the dance floor (dissolve into the water). Meanwhile, bicarbonate sets the tempo, making sure the dance doesn't get too wild and acidic. Together, they create a harmonious dance that results in a flavourful and balanced cup of coffee. But remember, just as too many dancers can overcrowd the floor, an excess of these minerals can lead to suboptimal extraction and an unpalatable brew.

An illustration for water solubles

How to Adjust Mineral Content in Coffee

  • Use a water softening system to reduce hardness and lower calcium and magnesium levels if you have hard water. 
  • Consider using a remineralisation filter or adding mineral concentrates, like Third Wave Water, to increase mineral content if your water is too soft or low in minerals. 
  • Mix distilled or reverse osmosis water with tap water to achieve a balanced mineral composition.

The Importance of Balancing pH in Perfecting Your Brew

The pH level of water plays a significant role in coffee brewing because it affects the extraction process and the overall taste of the coffee. Ideally, the water used for brewing should have a neutral to slightly acidic pH (around 6.5-7.5). If the water is too acidic or too alkaline, it can lead to imbalanced flavours, resulting in a sour or bitter taste in your coffee.

The pH level of water influences the solubility and extraction efficiency of coffee compounds, such as acids, sugars, and oils. Water with a slightly acidic pH is better at extracting these compounds, which contribute to the complexity and balance of flavours in your cup. On the other hand, water that is too acidic or too alkaline may cause certain compounds to be over- or under-extracted, leading to an imbalanced taste profile.

Additionally, pH affects the stability of coffee compounds during extraction. For example, some of the acids in coffee, such as chlorogenic acids, can degrade or break down into other compounds under extreme pH conditions. This degradation can impact the taste and aroma of the final brew.

A graph showing the sweet spot for pH coffee

You can think of the pH level in water as the conductor of an orchestra, guiding the musicians (coffee compounds) to create a harmonious and well-balanced performance (flavourful coffee). When the conductor maintains the right tempo (ideal pH), the musicians work in sync, and the orchestra delivers a captivating performance. However, if the conductor sets the tempo too slow (water is too alkaline) or too fast (water is too acidic), the musicians struggle to keep up, and the resulting performance is off-balance, leaving the audience (your taste buds) unsatisfied.

How to get the Perfect PH for your Coffee

  • Use a water filter with a pH-balancing component to adjust the pH level of your water. 
  • In some cases, you may add food-grade acids or alkaline additives, like citric acid or baking soda, to adjust the pH. However, this should be done with caution and in minimal amounts to avoid altering the flavour of your coffee. 
  • Experiment with bottled water that has a neutral or slightly acidic pH, as it may provide better results for your brewing process.

TDS: A Deeper Dive into Total Dissolved Solids and Coffee Flavour

Total Dissolved Solids (TDS) refers to the concentration of dissolved minerals, salts, and organic matter in water. TDS is an essential factor in coffee brewing, as it affects the extraction process and the taste of your coffee. Ideally, water for coffee brewing should have a TDS level between 75-250 parts per million (ppm). Water with too low TDS can result in weak or sour coffee, while water with too high TDS may lead to over-extraction and a bitter or astringent taste.

TDS affects the extraction efficiency and balance of coffee flavours by influencing the water's ability to dissolve and extract coffee compounds. Water with an appropriate TDS level has enough minerals and salts to interact with the coffee solubles, promoting proper extraction. However, if the TDS level is too low, the water will struggle to extract enough flavour compounds, leading to under-extraction. Conversely, if the TDS level is too high, the water might extract too many compounds, including undesirable ones, resulting in over-extraction and an imbalanced flavour profile.

A depiction of the graph that can be found on the MountZion TDS Matrix

The TDS Matrix by MountZION Coffee

A handy way to assess your coffee parameters is by using the MountZion TDS Matrix.

The TDS Matrix is an ingenious creation that helps you calculate the extracted percentage of coffee solubles, allowing you to optimize your brewing process and achieve the perfect cup. The equation at the heart of this tool is Extracted Percentage = (Beverage * TDS) / Dry Coffee.

By inputting these four values, you can gain valuable insight into the extraction process and adjust your brewing method accordingly.

To make the TDS Matrix even more accessible, the creator has thoughtfully included preset buttons at the top of the tool for different brew types. These presets offer suggested parameter inputs tailored to specific brewing methods. the (pictured graph is the output for a filter coffee), making it easy for you to find the right starting point for your preferred coffee extraction.

How to Optimise your TDS

  • Use a water filtration system that can control TDS levels, such as reverse osmosis systems with a TDS controller. 
  • Blend different water sources (e.g., tap water, filtered water, or distilled water) to achieve the desired TDS level. 
  • Test various bottled water brands to find one with a TDS level that suits your coffee brewing preferences.

Water Temperature: Finding the Sweet Spot for Espresso Extraction

Water temperature plays a critical role in espresso extraction, as it affects the rate at which coffee compounds dissolve and the overall taste of your espresso. The ideal water temperature for espresso extraction is typically between 90°C (195°F) to 96°C (205°F). Too low of a temperature can result in under-extraction and a sour taste (read more about sour tasting espresso and how to fix it), while too high of a temperature can cause over-extraction and a bitter taste.

The solubility and extraction efficiency of coffee compounds, including acids, oils, and sugars, are influenced by water temperature. Within the optimal temperature range, these compounds dissolve at a balanced rate, creating a well-rounded and flavourful espresso. Lower temperatures cause slower extraction rates, leading to under-extracted coffee with weak or sour flavours. Higher temperatures, on the other hand, speed up extraction rates, which can cause the extraction of undesirable compounds and result in over-extraction and bitter flavours.

Moreover, water temperature also affects the rate of chemical reactions that occur during coffee extraction. For example, the Maillard reaction, which is responsible for the development of rich, complex flavours and aromas, occurs more efficiently within the ideal temperature range.

What is the Ideal temperature for brewing coffee?

The ideal temperature for brewing coffee is between (195°F (91°C) and 205°F (96°C) can be influenced by factors such as TDS, pH, and mineral content, as well as coffee bean type, roast level, and grind size. Each of these factors can impact the extraction process and the resulting taste of the coffee.

  1. TDS: Water with higher TDS can extract coffee compounds more efficiently, which may require slight adjustments to the brewing temperature. For example, when using water with high TDS, you might want to use a slightly lower temperature to avoid over-extraction. 
  2. pH: The acidity of water can impact the extraction of certain coffee compounds. If the water is more acidic, you may need to use a slightly higher brewing temperature to counteract the increased extraction rate of acidic compounds and maintain a balanced flavour profile. 
  3. Mineral content: As discussed earlier, magnesium and calcium ions can enhance the extraction process. When using water with higher mineral content, you might consider adjusting the brewing temperature to maintain a balanced extraction. 
  4. Coffee bean type and roast level: Different roast levels of coffee beans and the different beans themselves have varying solubilities and extraction rates. Lighter roasts generally require higher brewing temperatures to extract the full flavour, while darker roasts may need slightly lower temperatures to prevent over-extraction and bitterness.

Water Filtration Systems for Coffee Enthusiasts

There are several levels of water filtration ranging from the totally suitable and reasonably priced to the totally overkill for most applications, however, you have probably now realised that making the perfect espresso does require some level of filtration of the water you’re using. Here are some of the best products around;

1. The Brita Filter

The Brita filter is the "go to" as an easily accessible option for general home water filtration. They use activated carbon filters to remove impurities, and are suitable for various brewing methods, including espresso, V60, cafetière, and moka pot. 

They are the first of three jug filter products in this list, but are probably the most available with the filters available online and in most supermarkets.

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Replacement Filters

2. BWT Water Filter Pitcher

A little more specialised, we use a BWT Bestmax inline filter in our Mobile Espresso Van which removes a lot of the impurities for our coffee, so as a brand, the BWT is tried and tested for brewing quality espresso. The jug works the same and has a variety of different levels of filtration depending on your water hardness. This pitcher might be considered overkill if you do not have hard water issues. However, if your water is particularly hard, this pitcher can help improve your coffee extraction and prevent scale build-up in espresso machines.

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Replacement Filters

3. The Peak Water Jug

The Peak Water Jug might be seen as overkill for casual coffee drinkers. However, for those who are passionate about coffee and want precise control over their water quality, it could be a worthwhile investment. This allows for gradual adjustment in the water filtration with its adjustable filter.

This is the cream of the crop of water filters and they can't seem to make them quick enough as they are almost always sold out. 

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4. iSpring Reverse Osmosis Filter

A reverse osmosis system like the iSpring Reverse Osmosis water filtration system converts water into clean, pure and healthy drinking water by removing up to 99% of over 1,000 harmful contaminants like chlorine, fluoride, heavy metals, TDS and more.

But rather than leaving a completely distilled water at the end of it, (which as discussed is bad for our application, it has an alkaline remineralisation filter which restores the natural alkalinity and mineral balance of water, which brings more natural taste to the water.

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Final thoughts

Monitoring and adjusting your water quality is essential for achieving the perfect cup of coffee. Factors like mineral content, pH, and total dissolved solids (TDS) can significantly impact coffee extraction and taste. By regularly testing your water and making necessary adjustments, you can ensure a consistent and delicious coffee experience.

In conclusion, the journey to brewing the perfect cup of coffee goes far beyond selecting high-quality beans and mastering various brewing techniques. It's crucial to recognise the significant role that water quality plays in the coffee-making process. From the mineral content and pH balance to the total dissolved solids, every aspect of your water has the potential to make or break your coffee's flavour profile.

By paying close attention to the water quality and making necessary adjustments, you can ensure that your coffee is consistently delicious and well-balanced. So, never overlook the importance of water quality in your quest for coffee perfection. Remember, it's the foundation that supports the intricate dance of flavours and aromas in your cup. By giving water the attention it deserves, you'll be one step closer to achieving coffee nirvana. Cheers to great coffee and the incredible difference that perfect water can make!


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