The answer in 30 seconds
- 💧 Water makes up about 98% of the cup: it matters as much as the beans.
- 🧪 Aim for low-mineral water, with total dissolved solids between 75 and 250 mg/l.
- 🚰 Filtered tap water works in most cases in Morocco.
- ⚠️ Demineralised water makes flat coffee: no minerals, no extraction.
Reading time: 7 min
We choose our coffee with care, our grind, our machine, and then fill the tank without a second thought. Yet water is the main ingredient in the cup. Water that is too hard crushes the aromas; water that is too pure doesn't extract them.
Why water changes the taste of coffee
The minerals dissolved in water act as carriers: magnesium latches onto aromatic and fruity compounds, calcium carries the bold notes and the body of the cup. Bicarbonates, meanwhile, neutralise acidity: very alkaline water erases the brightness of an Ethiopian and makes it flat. Conversely, with too few minerals extraction remains incomplete and the coffee comes out hollow and watery. In between, there is a fairly wide window in which the same coffee can produce very different cups.
Which water to use for great coffee at home?
There are four options, and they are not equal:
- Untreated tap water: free, but often hard and chlorinated in Morocco. Chlorine is immediately noticeable in the cup. Avoid as is.
- Filtered tap water, by jug or cartridge: reduces chlorine and some of the hardness. It's the best result-for-price option for everyday use.
- Low-mineral bottled water: excellent and perfectly repeatable results, but real cost and waste.
- Pure demineralised or reverse-osmosis water: avoid on its own. Without minerals, extraction doesn't happen and the coffee is flat.
The verdict: filtered tap water every day, low-mineral bottled water for tasting coffees, when you want to judge an origin without the water speaking for it.
Reading a mineral water label
Four lines are enough to decide in the aisle:
- Dry residue at 180 °C: aim for 75 to 250 mg/l, ideally around 150.
- Calcium: between 50 and 175 mg/l expressed as calcium carbonate. Above that, the machine scales up quickly and the cup gets heavy.
- Magnesium: a few dozen mg/l is enough; it's what carries the aromas.
- Bicarbonates: above a hundred or so mg/l, acidity fades and fruity coffees lose their depth.
Remember this simple rule: water sold as “rich in minerals” is precisely the one not to use for coffee.
Choosing your coffee water in 4 steps
- Test your tap water. A hardness test strip, from a pharmacy or appliance store, gives you the hardness in French degrees.
- Filter it if it's above 25 °f. Filter jug or cartridge on the machine: either way, change the cartridge as often as indicated, or it stops filtering anything.
- Compare blind. Two cups of the same coffee, same grind, same temperature, two different waters. It's the only test that counts for your palate.
- Settle on your water, then adjust the rest. Once the water is consistent, adjust grind and dose. Dialling in the grind with water that changes every time gets you nowhere.
The habit that changes everything: empty the tank every evening and refill it with fresh water in the morning. Water that has sat overnight in plastic gives a dull cup, whatever its mineral content.
Temperature and hardness: the two settings that matter
The ideal water for extraction is between 92 and 96 °C. Below that, coffee is under-extracted, sour and short; above it, it turns bitter and burnt. But a scaled-up machine can no longer reach this range: the heating element is insulated under a crust of limescale and the water arrives lukewarm. In other words, choosing the right water and maintaining the machine are two sides of the same problem — and hard water costs you on both fronts, in the cup and in the pipes. Frequency and method are detailed in our article How to descale a coffee machine.
When changing water isn't enough
Water doesn't explain everything, and it would be dishonest to suggest otherwise. If the cup is still disappointing after changing water, look at three other things. The grind first: too coarse, the coffee runs too fast and comes out sour; too fine, it's bitter. The freshness of the beans next: coffee ground several weeks ago has lost most of its aromas, and no water will bring them back. The machine finally: scaled up, or with seals and portafilter not cleaned, it hits a ceiling whatever you put in it.
THE COFFEE THAT REVEALS YOUR WATER
Ethiopian Mocha Sidamo Organic Coffee
Fruity and floral, with a bright acidity. It's precisely this profile that overly alkaline water flattens: ideal for comparing two waters blind.
Frequently asked questions
Which mineral water to choose for coffee?
A low-mineral water, with dry residue at 180 °C between 75 and 250 mg/l. Avoid mineral-rich and highly bicarbonated waters, which erase acidity and make the cup heavy.
Can you use tap water for coffee?
Yes, as long as you filter it if it's hard or chlorinated. Chlorine is directly noticeable in the cup and water above 25 °f scales up the machine quickly.
Is demineralised water suitable for coffee?
No, not on its own. Without minerals, water doesn't properly extract the aromatic compounds: the coffee comes out flat and watery. Some reverse-osmosis waters are remineralised, which is different.
Should you boil water before making coffee?
No. Boiling water, at 100 °C, burns coffee. Aim for 92 to 96 °C: with a basic kettle, let it rest about thirty seconds after boiling.
Does a filter jug really change the taste of coffee?
Yes, especially with chlorinated or hard water: it removes chlorine and some calcium. As long as you change the cartridge as often as recommended, otherwise the effect disappears.
Benchmarks and sources
- About 98% water in a cup of coffee: water is the main ingredient of the drink.
- Target dry residue around 150 mg/l, acceptable range 75 to 250 mg/l: Specialty Coffee Association brewing water standard.
- Calcium hardness of 50 to 175 ppm expressed as calcium carbonate, alkalinity around 40 ppm, pH between 6.5 and 7.5: same standard.
- Extraction temperature of 92 to 96 °C: reference range for brewing coffee.
- Above 25 °f, water is considered hard: filtration recommended and more frequent descaling.
Mineral values are tasting benchmarks, not health standards: drinking water remains safe to drink whatever its hardness.
Three coffees to test your water
Related articles
- How to descale a coffee machine: frequency and method
- Arabica vs robusta: what are the differences?
- Café crème, latte, cappuccino: homemade recipes
In short: water makes up about 98% of the cup. Aim for low-mineral water, between 75 and 250 mg/l of dry residue, filter your tap water if it's above 25 °f, and avoid both demineralised water and mineral-rich waters. Once your water is set, adjust grind and dose: in that order.
Our 100% arabica coffees are craft-roasted in France in small batches and delivered anywhere in Morocco in 2 to 5 days. Free delivery from 350 DH, cash on delivery.
