How to Choose the Right Water for Coffee

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Coffee is about 99% water — which means the quality of your water directly defines the quality of your cup. You can roast, grind, and brew everything perfectly, but if the water is wrong, the coffee won’t taste right. So how do you know which water is good, and which isn’t? Let’s break it down.

Why Water Matters

Water isn’t just a neutral liquid that “extracts coffee.” It’s an active participant in the brewing process.
When hot water meets coffee grounds, hundreds of flavor compounds dissolve into it — acids, sugars, oils, and aromatic molecules.
But water has a limited capacity to dissolve substances. If it already contains too many minerals (hard water), it can’t extract enough from the coffee. If it’s too pure (soft or distilled), it dissolves too much, making the brew overly acidic and harsh.

In simple terms:

  • Hard water → flat, dull coffee

  • Soft water → overly bright, acidic coffee
    The sweet spot lies somewhere in between — balanced water with the right amount of minerals.

Understanding Water Composition

Several measurable properties determine whether water is suitable for coffee:

1. Color and Odor

Clean water should be completely clear and odorless. Any chlorine smell, cloudiness, or metallic taste means the water isn’t suitable for coffee.

2. Mineral Content (TDS)

TDS — Total Dissolved Solids — shows how many minerals are in the water, measured in mg/L (or ppm).
For coffee, the SCA recommends water with a TDS between 75 and 250 mg/L, ideally around 90–130 mg/L.
This provides balance: enough minerals to carry flavor, but not so many that they mute it.

A good balance usually looks like this:

  • Calcium (Ca²⁺): 50–70 mg/L

  • Magnesium (Mg²⁺): 10–30 mg/L

  • Sodium (Na⁺): up to 10 mg/L

Calcium helps extract sweetness and gives body, while magnesium sharpens acidity and clarity. Too much sodium flattens the flavor.

3. Chlorine

Chlorine is added to city water for disinfection, but it creates a sharp, unpleasant taste.
For coffee, chlorine should be 0 mg/L — even small traces ruin aroma and taste.

4. pH Balance

pH measures acidity vs alkalinity.

  • Below 7: acidic → sour coffee

  • Above 7: alkaline → bitter coffee
    Ideal range: 6.5–7.5, with 7.0 being a safe neutral point.

5. Other Impurities

Iron, copper, and sulfur compounds — even in tiny amounts — can distort flavor. If you ever notice a metallic or sulfuric note, it’s likely from water, not the beans.

Tap Water, Boiled Water, or Distilled?

Let’s be honest: tap water in most Polish and European cities isn’t ideal for coffee.
It’s often too hard (250–400 mg/L TDS), full of calcium and chlorine, which make coffee dull and quickly create scale in your espresso machine.

Boiling water doesn’t help — it only precipitates calcium carbonate (scale), doesn’t remove chlorine, and can even concentrate impurities.

Distilled water, on the other hand, is too pure.
It contains almost no minerals, which means extraction becomes unbalanced — the coffee turns thin and overly acidic.
That’s why professionals often start from distilled or reverse-osmosis water and then add minerals back in controlled amounts.

Professional Filtration Systems

Roasteries and specialty coffee shops often use reverse osmosis (RO) systems like Everpure MRS-600HE, BWT Bestmax Premium, or Brita Purity C Quell ST.
These systems remove nearly all minerals and contaminants, and then let you blend back the right amount of mineralized water.

For cafés, it’s a game changer — consistent taste, protected machines, and precise control.
But for home use, such systems are overkill: large, expensive, and designed for hundreds of liters per day.

Home Solutions: Filters, Distilled Water, and Mineral Blends

For home baristas, there are three practical options:

1. Household Filters

Brands like Brita, Dafi, or AkVo are good choices.
Look for filters with softening and remineralization modules — they not only remove chlorine and heavy metals but also ensure the water contains the right amount of calcium and magnesium.

They’re cheaper long-term than bottled water, but results depend on your local tap composition. If your city water is too hard or soft, it’s worth testing it or experimenting with taste.

2. Distilled Water + Akvo Minerals

If you want ultimate control, start with distilled or RO water and add minerals yourself.
One of the best options for home users in Europe is AkVo, a Polish brand that provides precise mineral concentrates for coffee brewing.

Akvo Mineral Additives:

  • Clear Bottle – Potassium buffer + magnesium mix.
    Neutral flavor; good for most coffees. Use 3–5 drops per 0.5 L.

  • Pink Bottle – Sodium buffer + magnesium mix.
    Sodium neutralizes both pleasant and unpleasant aromas.

    • Bitter or fermented coffee → use more Pink

    • “Green” notes → mix 3–4 drops Pink + 1–2 Clear

  • Black Bottle – Ion blend for darker roasts.

  • Blue Bottle – Calcium. Usually 3 drops per 0.5 L.

After brewing:

  • For pour-over: 1 drop per cup (only one bottle).

  • For espresso: 1 drop per shot.

  • Common recipe: 3 drops Clear + 3 drops Blue per 0.5 L.

This way, you can make perfect “coffee water” with full control — no chlorine, no scale, just consistent flavor.

Bottled Water Options in Poland

If you prefer simplicity, bottled water can also work — as long as it has the right mineral balance.

Recommended Waters:

  • Żywiecki Kryształ: 220–230 mg/L TDS, pH ~6.6
    Recently reformulated — now more mineralized, producing fuller body and balanced sweetness. Suitable for most brew methods, but may cause scale in espresso machines if used daily.

  • Primavera: 251 mg/L TDS - great for balanced extraction, clear acidity, and structured body. Clean aftertaste.

  • Żywiec Zdrój: 130–150 mg/L TDS — light and balanced; great for filter brews.

  • Nałęczowianka: ~150 mg/L TDS — well-balanced for espresso and pour-over.

  • Kropla Beskidu: 130–150 mg/L TDS — soft, delicate flavor.

  • Staropolanka 2000: 150–160 mg/L TDS — slightly richer mouthfeel.

If in doubt, look for water labeled as low to medium mineralized (90–250 mg/L) and non-carbonated. Avoid sparkling or high-sodium waters.

Water Testing at Home

Curious how your water performs?
You can test it using a simple TDS meter (available for ~30–40 zł).
It won’t give you full mineral composition but helps check whether your water is within the target range (90–130 ppm).
If your reading is above 250 ppm, it’s likely too hard — try filtering or blending it with distilled water.

Key Takeaways

  • Water quality defines coffee quality — it’s 99% of your cup.

  • Ideal TDS: 90–130 mg/L, pH around 7.0, no chlorine.

  • Tap and boiled water usually don’t work — either too hard or unbalanced.

  • Distilled + remineralized water gives full control.

  • Akvo drops or suitable bottled waters are great for everyday brewing.

  • Regularly descale your machine if using mineral-rich water.

Final Thought

There’s no single “perfect” water — only the one that fits your taste and coffee style.
Light Ethiopian coffee may shine with softer water and a touch of magnesium, while rich Brazilian espresso often benefits from a bit more calcium.

Experiment. Take notes.
Because just like with roasting or brewing, great coffee starts with the right water.

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