Distilled water is essentially pure H₂O, with almost no dissolved minerals. It is the worst common choice for brewing.
Why it fails
Extraction depends on minerals. Magnesium and calcium ions bind to the flavour compounds in coffee and carry them into solution.
Without them, the water dissolves far less. What comes out is dominated by acids, with none of the sweetness or body that balances them.
What it tastes like
Hollow. A beginning and an end with nothing in between. Thin, flat, sometimes sour, with no sweetness and no discernible body.
People trying it for the first time often assume the coffee has gone stale.
The counter-intuition
The instinct is that pure water must be the cleanest starting point. It is the opposite — coffee needs a working solvent, not an inert one.
Where distilled water belongs
As a blank for recipe water. Distilled or RO plus a measured mineral dose is the most precise way to control brewing water, and it is what competition brewers use.
Never on its own.
In machines
Worse still. Very low-mineral water is corrosive to brass and copper, and many machines use conductivity probes for water level that fail entirely with pure water.
Some manufacturers explicitly void warranty for it.
The fix
Add minerals. A commercial sachet, or Epsom salt and a trace of bicarbonate.
The difference between distilled water and remineralised distilled water, same beans, is one of the most dramatic comparisons in coffee.
Last reviewed 8 August 2026