Remove chlorine from water: The key to avoiding off‑flavours

While chlorine is essential to guarantee the potability of municipal water, it is one of the brewer’s worst enemies. By interacting with phenols from malt and yeast, it creates molecules called chlorophenols, responsible for major aromatic defects.

A beer that reminds you of a "band-aid", a "hospital", or "burnt plastic"? The culprit is almost always chlorine. Fortunately, getting rid of it is extremely simple.

Chlorine treatment in brewing water

See our main dechlorinating product


1. Why should you dechlorinate your water?

Chlorine and chloramines (more stable and harder to remove) are not just about a bleach-like taste. The real danger is the chemical reaction during brewing:

  • Chlorophenols: These compounds have a very low detection threshold. Even a small amount of chlorine can ruin an entire batch with a persistent medicinal flavor.
  • Yeast health: In some cases, too high a concentration can stress your yeast during fermentation.


2. Method 1: Natural evaporation (The simplest)

Free chlorine is a volatile gas. If you’re not in a hurry, the most economical method is simply to let the water sit:

  • Action: Draw your total water volume 12 to 24 hours before brewing.
  • Condition: Leave the container open to allow the gas to escape.
  • Limitation: This method is ineffective against chloramines, increasingly used by municipalities because they do not evaporate.


3. Method 2: Campden (The “magic” method)

Potassium Metabisulfite (often known as Campden tablets) is the preferred solution among professionals to instantly neutralize chlorine AND chloramines.

The chemical reaction transforms chlorine into harmless chlorides in just a few seconds.

Metabisulfite Dosage Guide

Overdosing can inhibit yeast or produce a sulfur smell. Follow these doses carefully:

Tip: Mix the water well after adding it — the reaction is almost instantaneous.

The team’s tip

If you don’t know whether your water contains chloramines, always use Potassium Metabisulfite. It’s a very inexpensive insurance policy (just a few cents per batch) to ensure that no “pharmacy” flavor ruins your hard work.

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