Brewing Water Guide: Water Chemistry for Home Brewers

Water makes up around 90–95% of your beer, yet it's the ingredient most home brewers ignore. You don't need a chemistry degree to get it right. This guide explains what actually matters, starting with the one step every brewer should take, then working up to mineral additions and mash pH for all-grain brewers.

Do You Need to Worry About Water?

  • Kit and extract brewers: just remove the chlorine (Step 1). The minerals are already in the malt extract.
  • All-grain brewers: water chemistry makes a real difference to efficiency, flavour and clarity. Read on.
  • Wine, cider and mead makers: less critical, as most of the liquid is juice or honey, but treat the chlorine in any water you add.

Step 1: Remove the Chlorine (Everyone)

UK tap water is treated with chlorine or chloramine. Both react with compounds in beer to create chlorophenols: a medicinal, TCP-like or plasticky taste that's one of the most common home brew faults.

The fix is cheap and easy: crush one Campden tablet into up to 23 litres of water, stir and wait a few minutes. It removes both chlorine and chloramine. Leaving water to stand overnight only gets rid of chlorine, not chloramine, so a Campden tablet is the safer bet.

Step 2: Find Out What's in Your Water

Before adding anything, you need a starting point:

  • Your water company's report. Every UK supplier publishes water quality data by postcode, including hardness and often calcium, sulphate and chloride.
  • Water hardness test strips. A quick check of total hardness straight from your tap.

As a rough guide, the UK splits into two:

  • Soft water (Scotland, Wales, the Pennines and much of the North, including Calderdale): low in minerals. Great for pale beers and lagers, but may need calcium and sulphate for crisp, hoppy beers.
  • Hard water (London, the South East, East Anglia and the East Midlands): high in calcium and bicarbonate. Naturally suits darker beers, but often needs treating for pale styles.

Step 3: The Minerals That Matter

  • Calcium – the most important. Helps mash enzymes work, lowers mash pH, helps yeast drop out and improves clarity. Around 50–150 ppm suits most beers.
  • Sulphate – makes hop bitterness crisper and drier. The key mineral for pale ales and IPAs.
  • Chloride – gives a fuller, rounder, softer malt character. Suits stouts, milds, bitters and hazy IPAs.
  • Bicarbonate – raises mash pH. Useful in dark beers, which are naturally acidic, but a problem in pale beers.
  • Magnesium – a yeast nutrient in small amounts, but harsh above about 30 ppm.
  • Sodium – rounds out malt flavour in small amounts; tastes salty and harsh in excess (keep under about 100 ppm).

The sulphate-to-chloride balance matters more than the exact amounts. More sulphate than chloride pushes a beer crisp and bitter; more chloride than sulphate pushes it round and malty; roughly equal suits balanced beers like best bitter.

Step 4: Get Your Mash pH Right (All-Grain)

Mash enzymes work best at a pH of roughly 5.2–5.6. Too high and you get poorer extraction, harsh tannins and a dull, thin beer. Too low and the beer can taste sharp.

  • To lower pH (common with pale beers in hard water areas): add lactic acid powder (around ¼ teaspoon lowers a standard mash by about 0.1) or swap a little base malt for acidulated malt (about 1% of the grain bill lowers pH by around 0.1).
  • To raise pH (sometimes needed for very dark beers in very soft water): dark roasted malts are acidic, so a small amount of precipitated chalk can help. Note that chalk dissolves poorly, so stir it in well.

Your Water Treatment Toolkit

Product Adds Use it for
Campden tablets – Removing chlorine and chloramine (every brew)
Gypsum (calcium sulphate) Calcium + sulphate Crisp, hoppy pale ales and IPAs ("Burtonisation")
Calcium chloride flakes Calcium + chloride Fuller, maltier beers: stouts, milds, hazy IPAs
DWB water salts Calcium, chloride + sulphate An easy all-rounder blend for bitters and pale ales
Epsom salts (magnesium sulphate) Magnesium + sulphate Small tweaks only; use sparingly
Lactic acid powder Acidity Lowering mash pH
Acidulated malt Acidity Lowering mash pH naturally
Precipitated chalk Calcium + carbonate Raising pH for dark beers in soft water

Work out exact amounts with our free Water Profile Calculator.

Quick Guide by Beer Style

  • Pale ale and IPA: sulphate-forward. Add gypsum; lower pH with lactic acid if your water is hard.
  • Best bitter: balanced sulphate and chloride. DWB salts, or a mix of gypsum and calcium chloride.
  • Stout and porter: chloride-forward. Calcium chloride; dark malts will usually bring the pH down on their own.
  • Hazy IPA: chloride-forward for a soft, juicy mouthfeel. Calcium chloride.
  • Pilsner and pale lager: very soft water. Keep additions light, with a little calcium chloride and a touch of acidulated malt if needed.

Why Famous Beer Styles Come From Famous Water

Historic brewing towns developed their beers around their local water:

  • Burton-on-Trent: very high in sulphate, perfect for crisp pale ales and IPAs. Adding gypsum to copy it is called Burtonisation.
  • Dublin: hard and carbonate-rich, which balances the acidity of roasted malt in dry stout.
  • Pilsen: extremely soft, letting delicate malt and Saaz hops shine in Czech pilsner.
  • Munich: moderately carbonate-rich, suiting malty dark lagers.

Golden Rules

  • Always treat chlorine, whatever you brew.
  • Start small: a few grams of salts goes a long way.
  • Change one thing at a time so you can taste the difference.
  • Very hard or unpredictable water? Low-mineral bottled or reverse osmosis (RO) water gives you a blank canvas to build from.

Frequently Asked Questions

Does water matter if I brew beer kits?

Only the chlorine. The minerals are already in the malt extract, so just treat your water with a Campden tablet.

How do I remove chlorine from tap water for brewing?

Crush one Campden tablet into up to 23 litres of water and stir. It removes both chlorine and chloramine. Standing water overnight only removes chlorine.

What is Burtonisation?

Adding gypsum (calcium sulphate) to brewing water to copy the sulphate-rich water of Burton-on-Trent. It makes hop bitterness crisper and drier, ideal for pale ales and IPAs.

What pH should my mash be?

Roughly 5.2–5.6. Use lactic acid or acidulated malt to lower it, and chalk to raise it.

Is soft water good for brewing?

Yes. Soft water is a versatile starting point that suits pale beers and lagers well. Add gypsum for crisp, hoppy beers or calcium chloride for malty ones.

Ready to go all-grain? Start small with our guide to brewing beer on your hob, or read all-grain vs extract brewing.

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