Know your water

Before you add any salts, get a water report from your supplier or a home testing kit. UK water varies hugely: hard water in London and the South East is high in carbonate and alkalinity, pushing mash pH up and leaving beer harsh. Soft water in Scotland or the Lake District lacks minerals, giving flabby, dull beer. Focus on calcium, magnesium, sodium, sulphate, chloride and alkalinity. With those numbers, you can plan adjustments. If you can't get a report, start with bottled water or dilute your tap water with distilled water to reduce alkalinity.

Gypsum and calcium chloride

These two salts do most of the work. Both add calcium, which aids enzyme activity, yeast flocculation and clarity. Gypsum (calcium sulphate) accentuates hop bitterness – ideal for Burton-style pale ales and IPAs. Calcium chloride rounds out malt, boosts sweetness and body, and softens bitterness – perfect for stouts and porters.

For a 23-litre batch, start with 1–2 teaspoons (5–10g) of gypsum in the mash for hoppy beers, or 1–2 teaspoons of calcium chloride for malty ones. You'll often use both, tweaking the ratio. Always dissolve salts in warm water first – never dump them in dry. Add salts to the mash and sparge water before you heat it, so they dissolve fully. A few grams can make a noticeable difference, so weigh them if you can.

Mash pH matters

Target a mash pH of 5.2–5.4 at room temperature. Too high (above 5.6) extracts harsh tannins, lowers efficiency and makes hop bitterness coarse. Too low (below 5.0) gives a thin, acidic beer with poor head retention.

Alkalinity drives pH up. To reduce it, use carbonate reducing solution (CRS) as directed, or lactic or phosphoric acid in small increments, or up to 5% acidulated malt. Dark beers need less adjustment because roasted grains are acidic. Measure with a calibrated pH meter after 15 minutes, cooling the sample first. Paper strips aren't accurate enough. Remember that pH also affects hop bitterness: a lower mash pH gives a cleaner, more refined bitterness, while a higher pH can make it harsh and lingering.

Sulphate to chloride ratio

The ratio of sulphate to chloride is your main flavour lever. Around 2:1 sulphate to chloride pushes hops forward and dries the finish – great for IPA or bitter. Around 1:2 emphasises malt, sweetness and mouthfeel – ideal for milk stout or Scottish ale. 1:1 is balanced for English pale ales and brown ales.

Aim for total sulphate plus chloride between 150 and 300 ppm. For a Burton IPA, try 300 ppm sulphate and 50 ppm chloride. For a London porter, try 100 ppm sulphate and 200 ppm chloride. Write these targets down and adjust salt additions accordingly. Brew the same recipe twice with different ratios to learn your palate.

Putting it into practice

Here's a simple workflow. Get your water report. Decide your target profile. Use a free brewing water calculator to work out salt additions for your batch size, grain bill and water volumes. Add salts to mash and sparge water. Adjust pH with acid or acidulated malt, checking after 15 minutes. Add any remaining salts to the boil. Take notes – pH, salt amounts and tasting impressions.

• Hoppy pale ale: 1 tsp gypsum, 0.5 tsp calcium chloride per 23 litres, target pH 5.3.
• Malty stout: 0.5 tsp gypsum, 1.5 tsp calcium chloride per 23 litres, target pH 5.5.
• Balanced bitter: 1 tsp gypsum, 1 tsp calcium chloride per 23 litres, target pH 5.4.

You can also add salts directly to the boil for a more pronounced effect, but be careful not to overdo it. These are starting points. If your beer tastes too bitter and drying, reduce sulphate. If flabby and sweet, reduce chloride or increase sulphate. If harsh and tea-like, your pH was too high – bring it down next time.

Water chemistry is a conversation with your beer. Keep adjustments modest, log everything, and taste as you go. Over time you'll develop a house water profile that makes your best beers sing. Not just better efficiency or cleaner bitterness, but a character you can call your own. Start with small changes, brew often, and let your taste buds guide you.