DIY Brew Water Mineral Recipes: Pour Over Brewing Guide

Why Build Your Own Brew Water

Tap water varies wildly from city to city, season to season, and sometimes week to week. That variability makes it nearly impossible to reproduce a recipe consistently. When a barista in Oslo dials in a V60 with soft Scandinavian water and you try to replicate it in London with 300+ ppm hard water, you will get a fundamentally different cup. The coffee is the same. The grinder is the same. The water is not.

Building your own brew water from a blank slate — distilled or reverse osmosis water — and adding precise amounts of minerals gives you a consistent, repeatable base. You control the mineral content, which means you control extraction character. Once you find a water profile you like, you can reproduce it indefinitely, regardless of where you live or what comes out of your tap.

The concept is straightforward: start with empty water (distilled or RO), then add back specific minerals in known quantities. The minerals that matter most for coffee extraction are magnesium, calcium, and bicarbonate. Each plays a different role in how flavor compounds are pulled from ground coffee.

The Key Minerals and What They Do

Three mineral salts form the foundation of virtually every DIY brew water recipe:

Magnesium sulfate (Epsom salt, MgSO4-7H2O) contributes magnesium ions, which are efficient extraction agents. Magnesium has a strong affinity for many of the organic acids and fruity compounds in coffee. Water with a higher magnesium-to-calcium ratio tends to produce brighter, more complex cups with pronounced acidity. Epsom salt is food-grade, inexpensive, and widely available at pharmacies.

Calcium chloride (CaCl2-2H2O) contributes calcium ions, which are also extraction agents but with different flavor characteristics than magnesium. Calcium tends to emphasize body, sweetness, and heavier mouthfeel. It extracts flavor compounds less aggressively than magnesium, which can result in a rounder, smoother profile. Calcium chloride is available from brewing supply stores and online retailers. Make sure you purchase food-grade dihydrate form.

Sodium bicarbonate (baking soda, NaHCO3) contributes alkalinity — the buffering capacity that neutralizes acids during extraction. Bicarbonate is critical for balance. Too little and the cup will taste sharp, sour, and astringent. Too much and it flattens acidity, producing a dull, chalky cup. Bicarbonate acts as a chemical buffer, absorbing hydrogen ions produced by the organic acids in coffee. Standard grocery store baking soda works perfectly.

Some recipes also include potassium bicarbonate (KHCO3) as an alternative or supplement to sodium bicarbonate. Potassium contributes alkalinity without adding sodium, which some tasters find can introduce a slightly salty or mineral taste at higher concentrations.

Making Mineral Concentrates

Rather than weighing tiny amounts of minerals for each brew, the standard approach is to make concentrated stock solutions. You dissolve a measured amount of each mineral salt into a known volume of distilled water, creating a concentrate. Then you add small volumes of concentrate to your brewing water using a syringe or pipette.

A common concentration is designed so that 1 mL of concentrate added to 1 liter of distilled water contributes a specific, round number of ppm. This makes the math simple.

Barista Hustle concentrate protocol:

• Epsom salt concentrate: dissolve 2.45 g of MgSO4-7H2O into 500 mL of distilled water. Each 1 mL added to 1 L of brew water contributes approximately 1 ppm of magnesium as CaCO3 (general hardness).
• Baking soda concentrate: dissolve 1.68 g of NaHCO3 into 500 mL of distilled water. Each 1 mL added to 1 L of brew water contributes approximately 1 ppm of alkalinity as CaCO3 (KH).

Store concentrates in clean glass or BPA-free plastic bottles, labeled clearly. They remain stable for months at room temperature. Shake before use.

To use: decide on your target GH and KH values in ppm as CaCO3, then add that many mL of the respective concentrate per liter of distilled water. For example, if you want 60 ppm GH and 40 ppm KH, add 60 mL of the Epsom salt concentrate and 40 mL of the baking soda concentrate to enough distilled water to reach 1 liter total volume.

For calcium-based recipes, you can make a separate calcium chloride concentrate: dissolve 2.22 g of CaCl2-2H2O into 500 mL of distilled water. Each 1 mL per liter of brew water contributes approximately 1 ppm of calcium hardness as CaCO3.

Popular Recipes

Barista Hustle Water Recipe

The Barista Hustle recipe, developed by Matt Perger, is one of the most widely used starting points:

• GH (general hardness): 50-60 ppm as CaCO3 (magnesium-based)
• KH (alkalinity): 40 ppm as CaCO3
• Total TDS: approximately 90-100 ppm

This produces a balanced, slightly bright cup that works well across a range of roast levels and origins. The magnesium-forward profile tends to highlight acidity and fruit notes.

Rao/Perger Water

Scott Rao’s preferred water profile pushes slightly harder on hardness while keeping alkalinity moderate:

• GH: 70-75 ppm as CaCO3
• KH: 35-40 ppm as CaCO3
• Ratio of GH to KH roughly 2:1

This recipe aims for a sweet spot where extraction is efficient but buffering prevents harshness. The higher hardness relative to alkalinity allows more organic acids to come through, resulting in a lively cup.

Third Wave Water

Third Wave Water sells pre-measured mineral packets designed to be added to one gallon of distilled water. The Classic profile targets approximately:

• Calcium: ~45 mg/L
• Magnesium: ~15 mg/L
• Sodium: trace
• TDS: approximately 150 ppm
• Alkalinity: moderate

The convenience factor is the primary appeal. No weighing, no concentrates, no math. Tear open a packet, pour it into a gallon jug of distilled water, shake, and brew. The Classic profile uses a blend of calcium citrate, magnesium sulfate, and sodium chloride. Third Wave Water also offers an Espresso profile with lower mineral content to reduce scale buildup in machines.

Jonathan Gagne’s Recipes

Jonathan Gagne (coffeeadastra.com) has published extensively researched water recipes based on systematic extraction experiments. His approach emphasizes understanding the ratio of hardness to alkalinity and how it shifts extraction yield and flavor balance. Gagne’s work suggests that the optimal hardness-to-alkalinity ratio depends on the specific coffee and roast level, and he provides multiple recipes targeting different flavor profiles:

• A high-magnesium recipe for bright, acidic coffees
• A balanced calcium-magnesium blend for medium roasts
• A lower-hardness recipe for dark roasts where aggressive extraction is undesirable

Gagne’s writing is particularly valuable because he connects water chemistry to measurable extraction yields using a refractometer, bridging the gap between mineral content and what ends up in the cup.

Melbourne Water by Lesley Fung

Lesley Fung’s recipe, sometimes called the “Melbourne recipe,” targets:

• Magnesium: 30 ppm as CaCO3
• Calcium: 30 ppm as CaCO3
• Bicarbonate: 40 ppm as CaCO3

This 50/50 split between calcium and magnesium is designed to capture the body-enhancing properties of calcium alongside the brightness of magnesium. It represents a middle-ground philosophy.

Equipment You Need

Building brew water requires minimal equipment, most of which costs less than a bag of specialty coffee:

• Precision scale capable of reading to 0.01 g (a jewelry scale works well, typically $15-25)
• Distilled or RO water as your base (available at any grocery store, or from a home RO system)
• Food-grade mineral salts: magnesium sulfate (Epsom salt), calcium chloride (dihydrate), sodium bicarbonate (baking soda)
• Measuring syringes or pipettes for dispensing concentrates (1 mL and 10 mL syringes are most useful)
• Clean bottles for storing concentrates (500 mL or 1 L glass bottles with caps)
• A TDS meter (optional but useful for verification, $10-20)

A TDS meter measures total dissolved solids and can confirm your water is in the expected range. It will not tell you the specific mineral composition, but it catches gross errors like forgetting to add a concentrate or accidentally doubling a dose.

Step-by-Step: Making Your First Batch

1. Start with distilled water. Verify it reads 0-5 ppm on a TDS meter. If it reads higher, the water may not be truly distilled or your meter needs calibration.

2. Make your concentrates. Using the Barista Hustle ratios above, weigh 2.45 g of Epsom salt and dissolve it in 500 mL of distilled water. Separately, weigh 1.68 g of baking soda and dissolve it in another 500 mL of distilled water. Label each bottle clearly.

3. Choose a recipe. For your first batch, the Barista Hustle recipe (50 GH / 40 KH) is a reliable starting point.

4. Measure and add concentrates. Into a clean 1-liter bottle, add 50 mL of the magnesium concentrate and 40 mL of the baking soda concentrate using syringes. Fill the rest of the volume with distilled water to reach 1 liter total.

5. Shake and verify. Shake the bottle to mix thoroughly. A TDS meter should read approximately 90-100 ppm.

6. Brew and taste. Make your usual recipe with the new water and compare it to a cup made with your tap water. The difference is often immediately obvious.

Adjusting Recipes to Taste

Once you have a baseline, you can tweak the mineral profile to shift flavor:

• Want more brightness and acidity? Increase GH (hardness) relative to KH (alkalinity), or shift the hardness source toward more magnesium.
• Want more body and sweetness? Shift hardness toward calcium, or increase KH slightly.
• Cup tastes flat or chalky? Reduce KH. Excess alkalinity neutralizes too much acidity.
• Cup tastes sharp, sour, or astringent? Increase KH. Insufficient buffering lets too many acids through.
• Cup tastes hollow or thin? Increase GH. The water may not have enough extraction power.

Small changes matter. Adjusting GH or KH by 10-20 ppm can produce a noticeable shift in the cup. Make one change at a time and taste the difference before making further adjustments.

Common Mistakes

Using tap water as a base instead of distilled. The entire point is starting from a known baseline. Tap water already contains minerals in unknown proportions. Adding concentrates to tap water gives unpredictable results.

Confusing ppm as CaCO3 with ppm as the ion. Water chemistry uses calcium carbonate equivalents as a standard unit, which is different from the actual concentration of a given ion. Most brew water resources report values as CaCO3. Make sure you know which unit a recipe uses before following it.

Neglecting alkalinity. Some early DIY recipes focused only on hardness and ignored bicarbonate entirely. The result is aggressive extraction with no buffering — a sharp, sour cup. Alkalinity is not optional.

Making concentrates with tap water. This defeats the purpose. Always use distilled or RO water for both concentrates and the final brew water.

Over-engineering it. Start with one proven recipe, use it for a few weeks, and learn how it tastes across different coffees before you start tweaking. The goal is consistent good coffee, not a chemistry project.

Storage and Shelf Life

Mineral concentrates stored in sealed bottles at room temperature remain stable for several months. There is no biological component to spoil, but over very long periods mineral salts can precipitate out of solution, especially calcium-based concentrates. If you see visible crystals or cloudiness, shake vigorously before use or make a fresh batch.

Finished brew water (distilled + concentrates) can be made in larger batches — 5 or 10 liters at a time — and stored indefinitely. Many people keep a large jug of premixed brew water next to their kettle, refilling it weekly from concentrates.