Brewing with Competition Water: A Brewers Cup Journey

Embracing the Challenge of Compulsory Water

I was thrilled to take 2nd place at the Central Region Brewers Cup Championship, but getting there required an unconventional approach. In most competitions and daily brewing, I tailor my water’s mineral composition precisely to each coffee. Water isn’t just a solvent – it’s over 98% of the final brew, and its mineral makeup dramatically influences flavour. However, this championship posed a unique challenge: I couldn’t use my own customised brewing water. Competitors had to brew with a provided “compulsory” water, of unknown composition. Rather than viewing this as a setback, I saw an opportunity to apply coffee science in real time.

After years of crafting my own water recipes, I essentially reversed the process for this event. I took a sample of the competition’s water and ran a detailed laboratory analysis on it. My goal was to reverse-engineer its mineral profile so I could adjust my coffee choice and technique to suit the water, since I couldn’t adjust the water itself. This first-person account will delve into my water analysis, how it compared to APAX LAB’s recommended values, and how I navigated mineral imbalances to still bring out the best in my coffee. Along the way, I’ll reference APAX LAB’s ion synergy research and visual models that guided my strategy.

Analysing the Competition Water

The lab analysis of the competition water revealed a distinct mineral breakdown. The water had a moderate total mineral content (within specialty coffee’s ideal range of ~50–150 ppm (apaxlab.com) but the balance of ions was far from what I would normally design. In particular, it was calcium, chloride and magnesium-light, with a relatively high level of sodium and bicarbonate:

• Calcium (Ca²⁺): 4 mg/L – a very low amount, contributing to sweetness and body.
• Magnesium (Mg²⁺): 6.2 mg/L – low concentration, meaning the fruitiness and vibrancy will be lacking
• Sodium (Na⁺): 20 mg/L - a very high sodium concentration which can lead to an overpowering intensity
• Potassium (K⁺): 2 mg/L - potassium virtually absent, making the aftertaste short, and the body and acidity less intense.
• Bicarbonate (HCO₃⁻): ~67 mg/L – corresponding to about 53 ppm as CaCO₃ alkalinity, which is on the higher side for brew water.
• Chloride & Sulfate (Cl⁻, SO₄²⁻): ~25 mg/L Cl⁻, ~1 mg/L SO₄²⁻ (estimated) – some chloride but not enough to boost the sweetness and texture - and virtually no sulfate anions, normally great to bring intensity and length in the cup.

For context, APAX LAB’s recommended water profiles for optimal extraction focus on balanced ion levels to enhance specific sensory attributes of coffee. Typically, we recommend maintaining Calcium (Ca²⁺) between 8–15 mg/L to enhance sweetness and body, Magnesium (Mg²⁺) between 20–35 mg/L to boost brightness and complexity, and keeping Bicarbonate (HCO₃⁻) low, around 6–15 mg/L, to preserve acidity and clarity.

Comparing these targets to the competition water: it was clear the supplied water’s Mg²⁺ was only a fraction of what I’d normally use, and its bicarbonate was nearly double what we’d recommend. The calcium and chloride were low than ideal as well. This ion imbalance had important implications for how coffee would taste.

Ion Imbalances and their Flavour Impact

Water chemistry can be technical, but its impact on flavour is very tangible. APAX LAB’s ion synergy research has shown that no single ion works in isolation – it’s the interplay of minerals that shapes the final cup. In this case, the competition water’s profile was likely to push the brew in certain directions. Based on the analysis, I anticipated a few key effects:

• Low Magnesium (Mg²⁺) → Muted Acidity: Magnesium is a crucial ion for enhancing brightness and lively acidity in coffee. In our experience and research, Mg²⁺ “brings out bright fruit notes” and contributes significantly to a coffee’s vibrancy. With the water almost devoid of magnesium, I knew the brew might lack some of the sparkle or high-note acidity that Mg usually amplifies. In other words, a coffee brewed with this water could taste flat or dull in the acidity department if the coffee itself, the roast or the brewing technique didn’t compensate.
• High Bicarbonate (HCO₃⁻) → Suppressed Brightness: Bicarbonate is the main component of alkalinity, which buffers (neutralises) acids. Some alkalinity is helpful to prevent overly sour brews, but too much will flatten a coffee’s brightness. A high HCO₃⁻ level mutes acidity, suppressing the lively brightness and even causing a chalky texture when paired with high calcium. In this water, the alkalinity of ~50 ppm (as CaCO₃) was quite elevated. I expected it to tame the coffee’s acidity and potentially dull complex flavour clarity. This meant a delicate, acidity-driven coffee might struggle to shine.
• Low Calcium → Lacking Body : Calcium contributes to body and fullness in the cup. In fact, calcium tends to intensify body. With calcium being in low concentrations, the water would likely create a lack in the coffee’s body/mouthfeel. The mouthfeel might be watery and light.
• Moderate Chloride → Slight Sweetness and Clarity: There was a bit of chloride in the mix. In small amounts, it can actually enhance roundness and sweetness. Chloride sitting at ~25 ppm is relatively low and generally helps smooth out harsh edges. I wasn’t too worried about it ; at these levels, it’d likely have mild positive effects or remain neutral.
• High Sodium → Intense Flavours: There was a high amount of sodium, which typically brings intensity, much like salt seasoning food. The provided water’s sodium was above my recommended range, but not enough to taste salty, but possibly enough to boost perception of sweetness/umami.

In summary, the compulsory water was geared toward low acidity and body. If I brewed a coffee with subtle body or one that relies solely on a gentle acidity, the result could be underwhelming – thin and lacking sparkle, intense but perhaps one-dimensional. On the other hand, this water could support a coffee with big body, sweetness and bright acidity, as those attributes wouldn’t be suppressed. My challenge was clear: I needed to choose a coffee, and brew method, that would synergise with this water rather than suffer from it.

Adapting through APAX Ion Synergy Principles

Equipped with the water’s profile, I leaned on the principles we champion at APAX LAB regarding ion synergy. Years of research have taught us that it’s not just about having the “right” ions, but having them in the right proportions. Since I couldn’t change the proportions in the water, I had to adapt everything else to achieve balance in the cup.

One useful tool in understanding this was the APAX Ion Chart, a visual model we developed to map how each ion influences coffee flavour. It plots ions on two axes – brightness (vertical) and body (horizontal) – to illustrate their sensory contributions. For example, magnesium sits high on the brightness scale (it might be plotted around 5 on brightness but only ~2 on body), whereas calcium lies more to the right on the body axis (contributing strongly to body, less to brightness). Bicarbonate, tellingly, appears far to the body side and low on brightness – indicating it adds heft but can dull acidity.

The APAX Ion Chart visually maps key brewing ions by their impact on brightness (y-axis) versus body (x-axis). Each ion’s position shows its relative influence, and the triangle size illustrates its “dose ceiling” (how much can be used before negative effects). For instance, magnesium (Mg²⁺) scores high on brightness but modest on body, whereas calcium (Ca²⁺) tilts toward body. Bicarbonate (HCO₃⁻) lies low on brightness and high on body, aligning with its tendency to reduce acidity and increase heaviness. Small triangles like Na⁺ and HCO₃⁻ warn that only a little is needed before taste balance tips.

This chart (and the research behind it) guided my strategy. It confirmed that the water I had was heavy on body-contributing ions (Ca²⁺, HCO₃⁻) and light on brightness boosters (Mg²⁺, K⁺). Put simply, the water would push the cup’s flavour towards fullness and low acidity levels. To achieve flavour harmony, I needed to supply what the water lacked and temper what it had in excess. That meant selecting a coffee and crafting a brew recipe that would inject brightness, acidity, and sweetness to counterbalance the water, while leveraging the water’s body-enhancing nature to produce a rounded, sweet cup.

Coffee Choice: Sudan Rume Natural from CGLE, Colombia

After considering the water’s profile, I decided on a coffee that could stand up to these conditions: a Sudan Rume Natural from Café Granja La Esperanza (CGLE) in Colombia. This choice was very intentional. The Sudan Rume variety is a variety known for its exceptional botanical and ginger notes, great sweetness and intensity. In the hands of CGLE’s expert processors, it yields a coffee with high inherent sweetness, vibrant acidity, and heavy body – exactly the traits I needed to complement the water.

I had used this coffee in competition, so I was familiar with its flavour profile. It’s a stunning natural-processed lot that bursts with fruit and sweetness. Common flavour notes include floral tones, lemongrass, ginger, tropical fruits, and berries, all wrapped in a syrupy body. In fact, this coffee is described as elegant, floral and sweet by the producer. The natural processing accentuates its sweetness and heavier mouthfeel, giving it a lush, layered character.

Why was this Sudan Rume a great match for the water? Let’s break down the synergy:

• Brightness and Acidity: The coffee has a bright, fruity acidity (think citrus and tropical fruit tartness) that is quite pronounced. The water was going to mute some acidity, but this coffee had brightness to spare. Even if the high bicarbonate neutralised a portion of the acids, enough would still shine through to keep the cup lively. Essentially, the coffee’s starting point on acidity was so high that the water would knock it down to “just right” rather than flat. Many less acidic coffees would have tasted dull under these conditions, but the Sudan Rume’s vibrant tartness gave us a buffer.
• Sweetness: Natural processing often amplifies sweetness and fruitiness, and indeed this lot is loaded with natural sugars and fruity sweetness. The presence of sodium in the water (and the chloride) could actually help emphasise that sweetness on the palate. Moreover, since the water’s lack of magnesium could reduce perceived sweetness slightly (because Mg²⁺ can enhance sweet, fruity notes, having a coffee that is inherently sweet ensured the cup would still taste sweet and pleasing). The water’s minerals acting like “seasoning” – a pinch of salt from NaCl – might even boost the sweet impression, making the coffee’s rich notes pop.
• Body and Mouthfeel: Sudan Rume is known for a round, full body. This pairs nicely with the water’s low calcium levels, which would balance the lack of body and give a satisfying weight to the cup. The risk with a low-bodied water is that a delicate coffee might feel too watery or thin; but this coffee starts with a robust mouthfeel that could carry that lack of calcium with grace. The result would be a competition brew that feels luxurious and coating on the tongue – an attribute judges appreciate, as long as it’s not dry or overbearing. I was mindful that too much Ca/HCO₃ can dry out the finish, but the coffee’s fruit oils and natural sweetness helped maintain a juicy, long aftertaste rather than a dry or chalky finish.
• Complexity and Aroma: This Sudan Rume has layered complexity (florals, spices, fruit). I found that the water’s composition, while dulling acidity, did not significantly impede aroma extraction. In fact, ions like K⁺ and SO₄²⁻ (though minor here) can enhance florals and depth – for instance, magnesium sulfate is known to accentuate floral notes. Any sulfate present in the water could synergise with the coffee’s inherent florals (e.g. the noted eucalyptus/ginger aroma), and the potassium present in the coffee beans themselves would contribute to sweetness and aftertaste. The end result was a brew that still showcased the coffee’s stunning aromatic profile, with the water contributing a round structure.

In choosing the Sudan Rume Natural, I effectively picked a coffee that filled in the gaps left by the water and took advantage of the water’s strengths. I also made slight adjustments to my brewing method to accommodate the water: for example, I ground a touch coarser than usual to accentuate the acidity. I also opted for a shorter ratio, aiming to maximise flavour concentration and get every bit of sweetness out. These brewing tweaks, combined with the coffee selection, were all about achieving balance.

Results in the Cup

On the stage, as I brewed my competition coffee with this carefully planned approach, I was essentially conducting a flavour symphony between the fixed water and the chosen coffee. The outcome was immensely satisfying. The cup was sweet, full-bodied, and balanced, with a pleasant bright note that cut through the richness. Judges noted the round mouthfeel and juicy citurs fruit notes, underpinned by a delicate florality. The brightness wasn’t as sharp as it might have been with my own ideal water, but it was enough to give the cup life and complexity. In fact, one could argue the slightly softened acidity contributed to a more integrated flavour experience, allowing the sweetness and body to take centre stage without any one attribute overwhelming the cup.

Placing second was a proud moment, but more than the trophy, I was proud of how science and technique turned a potential disadvantage into an advantage. By understanding the water, I was able to bring out a flavour profile that felt intentional and harmonious, rather than fighting against an unknown variable. This experience reinforced for me that water, coffee, and brewing method form a holistic system – and as a barista or competitor, the more you understand each component (especially the often-overlooked water), the more control you have over the final cup.

Takeaways and APAX LAB Recommendations

This Brewers Cup experience yielded valuable lessons that extend beyond competition. Whether you’re on a championship stage, behind the bar at a café, or brewing at home, understanding your base water is foundational to proper coffee extraction. Here are some practical recommendations from my experience and APAX LAB’s water science insights:

1. Know Your Water – Always start by assessing your water. If you can, get a water analysis (even a basic test). It’s impossible to predict how to best brew your coffee without knowing what you’re brewing with. As our research emphasises, water’s ion balance dramatically alters flavour balance. Even if you can’t change your water, knowing its profile will guide your coffee choice and recipe.
2. Adjust What You Can – In regular scenarios, you can often adjust the water: use filters, or mix your own water using mineral concentrates. APAX LAB was founded on making this easier – for instance, our mineral kits allow you to craft water with the exact ion profile you desire. If you have hard water at home, consider diluting with distilled or using a formulated recipe to hit that sweet spot of ~90 ppm TDS with balanced minerals. There’s no one “perfect” water for coffee – the perfect water depends on the coffee and desired profile – but you can aim for a balanced starting point and then tweak for specific beans.
3. If You Can’t Change the Water, Change the Coffee (or Recipe) – As I did with the compulsory water, choose a coffee that thrives with your water’s profile. If your water is very soft (low minerals), you might pick a coffee known for high body or use a recipe that extends extraction to avoid thinness. If your water contains a lot of bicarbonate, perhaps avoid darker roasted, low-acidity coffees that will taste flat, and instead go for naturally bright, juicy coffees that still taste vibrant. You can also adjust your brew parameters: grind, dose, temperature, and brew time are all levers to adjust all the attributes.
4. Balance is Key – Remember that coffee brewing is a game of balance. It’s not just about the right minerals, but the right proportions. Too much of even a beneficial ion can turn the flavour corner from good to bad. For example, magnesium is great for vibrancy, but push it too high and you get bitterness or a metallic finish; a pinch of bicarbonate smooths acidity, but too much and the coffee tastes dull. Use tools like the ion chart or recommended ranges as a guide, and taste the results. Your palate will tell you if you’ve hit the mark.
5. Continuous Learning – Finally, approach water like you do coffee beans: with curiosity and willingness to experiment. The field of water for coffee is evolving, with new research (like APAX LAB’s ongoing studies into ion synergy) shedding light on subtle interactions. Engage with visual models and resources – for instance, the APAX Ion Chart or our blog articles – to build your intuition. The more you connect the theory to what’s in your cup, the better you’ll get at dialling in delicious coffee no matter the water.

In the end, water chemistry doesn’t have to be intimidating. It can be the secret weapon in a barista’s arsenal, turning a good brew into an exceptional one. My Brewers Cup journey is a testament to that: by not overlooking water and by understanding its role, I could confidently adapt and still brew an award-winning cup. For competitors, baristas, and café owners alike, the message is clear – invest time in your water. It’s the foundation of every coffee you make, and with a solid foundation, you can build something truly outstanding in the cup.

Understanding and respecting your water will unlock new heights in coffee flavour and ensure that every extraction is as precise and rewarding as possible. Water may be invisible in the final cup, but its impact is monumental – harness it to your advantage, and you’ll taste the difference it makes. Here's to brewing coffee that’s not just good, but the absolute best it can be, through science, synergy, and a bit of creativity.