Two Concentrates for Coffee Water: 3 Tested Recipes for Home Brewers
Make your coffee water from distilled or reverse osmosis water plus two mineral concentrates: magnesium sulfate (Epsom salt) for hardness and sodium or potassium bicarbonate for buffering. Pick a tested starting recipe by brew method: Barista Hustle for pour-over, Rao water for espresso, or a Third Wave Water clone for fuller-bodied drip and cupping.
TL;DR:
- Using distilled or reverse osmosis water provides a predictable base, making mineral additions more precise and consistent across batches.
- Magnesium favors sweeter, brighter extraction and is less prone to scale formation, whereas calcium adds body but builds scale faster over time.
- Recipes like Barista Hustle, Rao water, and Third Wave Water clone differ mainly in hardness and alkalinity levels, matching specific brewing methods and roast profiles.
- Concentrates are best prepared in bulk, stored properly, and dosed with a syringe to ensure accuracy, especially when scaling for larger batches.
- Adjust water mineral content based on cup taste: increase alkalinity to mellow sourness, hardness to boost body, and reduce both if the cup tastes muddy or bitter.
Table of Contents
- Why base water matters and how each mineral influences extraction
- Equipment and measurement: what to buy and why
- How to make the two mineral concentrates
- Three tested recipes with per-liter dosing and best uses
- Scaling recipes for bigger batches and simpler measuring
- Adjusting recipes for brew method, roast, and taste
- Safety, machine care, and storage cautions
- How Moustache Coffee Club pairs ultra-light roasts with water recipes
- When DIY water is worth it and when it is not
- Try your next water recipe with beans that show the difference
- Sources
- FAQ
Why base water matters and how each mineral influences extraction
Tap water carries an unpredictable mix of minerals, chlorine byproducts, and regional quirks that change every time you fill the kettle. Starting from distilled or reverse osmosis (RO) water strips that variability out, giving you a blank slate where every milligram of mineral you add is a milligram you chose. That predictability is the entire point of building your own coffee water: you cannot dial in a recipe if your starting point shifts month to month.
Once you have a blank base, two mineral families do almost all the work. Hardness, driven mainly by magnesium (Mg2+) and calcium (Ca2+), increases what brewers call extraction power: harder water tends to pull more soluble compounds out of the grounds. Alkalinity, carried by bicarbonate (HCO3-), acts as a buffer against the acids released during brewing, softening or rounding out sourness depending on how much you add.
The two minerals are not interchangeable. Magnesium and calcium both add hardness, but they behave differently in the cup and in the machine:
- Magnesium tends to favor sweeter, brighter extraction and is less prone to forming stubborn limescale than calcium.
- Calcium adds body and hardness quickly but builds scale more aggressively over repeated brews.
- Bicarbonate buffers acidity, which matters more for espresso than for filter coffee since alkalinity adjustments help espresso manage acidity more than they change filter extraction.
- Distilled or RO water with zero minerals extracts almost nothing on its own, which is why it works only as a base, never as a finished brewing water.
The Specialty Coffee Association publishes practical target ranges for brewing water, including total dissolved solids around 150 mg/L and calcium hardness in the 40 to 70 mg/L range. Those numbers exist because reproducibility matters more than any single mineral being “correct.” A shop in one city and a home brewer in another can hit the same cup profile only if they are working from the same numeric targets rather than whatever comes out of their tap.
Equipment and measurement: what to buy and why
You do not need a laboratory to build repeatable coffee water, but a few cheap tools separate consistent batches from guesswork. Start with your base water: distilled water from a grocery store or pharmacy is the simplest option, and RO systems pay for themselves if you are brewing daily. Either source gives you the same mineral-free starting point, so buy whichever is easier to keep stocked.
For measuring, precision matters more than volume:
- A jewelry or coffee scale accurate to 0.01 g is the single most useful purchase, since concentrate recipes are dosed in single-digit grams per liter.
- Plastic syringes (1 mL to 10 mL) let you dose liquid concentrate into brewing water far more accurately than pouring.
- Labeled bottles for each concentrate prevent the classic mistake of dosing bicarbonate when you meant magnesium sulfate.
- A permanent marker or printed labels noting concentrate strength and mix date keep batches from turning into mystery liquids in the back of the fridge.
Optional gear like a TDS pen or pH strips is worth adding once you are tweaking recipes rather than just following one. A TDS pen confirms your finished water lands near the target range, while pH strips give a rough sanity check on buffering. Neither is required to make good coffee water, but both shorten the feedback loop when you are troubleshooting a cup that tastes off.
There are two ways to actually get minerals into your water: weighing salts directly into each brewing batch, or making a concentrate once and dosing small volumes each time. Direct weighing is more exact per batch but demands a scale precise enough to measure fractions of a gram, which most kitchen scales cannot do reliably. Concentrates trade a small amount of upfront effort for weeks of fast, repeatable dosing, which is why most published recipes, including Barista Hustle’s, default to the concentrate method.
Pro Tip: Keep your concentrate bottles and your finished brewing water in different-shaped containers so you never grab the wrong one by muscle memory.
Good filtration habits matter even before you start mineralizing anything, and understanding why filtered water changes coffee flavor helps explain why starting from a clean base pays off downstream.
How to make the two mineral concentrates
Building your own coffee water comes down to two concentrates: one for hardness, one for buffering. Both use ingredients you can find at a pharmacy or grocery store, and both scale predictably once mixed.
- Buy food-grade, unscented Epsom salt (MgSO4·7H2O) and baking soda (NaHCO3). Avoid scented bath-salt versions of Epsom salt since fragrance additives are not meant for consumption.
- Make the hardness concentrate by dissolving 24.6 grams of MgSO4·7H2O into 1 liter of distilled water, stirring until fully clear.
- Make the buffer concentrate by dissolving 16.8 grams of NaHCO3 into a separate liter of distilled water, again until no granules remain visible.
- Label each bottle immediately with the contents, concentration, and mix date before you set it down, since both liquids look identical once dissolved.
- Store both concentrates in the refrigerator in sealed bottles, and use them within a few weeks for best results.
The math behind these concentrates is simpler than it looks. Each gram of MgSO4·7H2O or NaHCO3 dissolved into a liter of concentrate contributes roughly 10 mg/L of hardness or alkalinity (as CaCO3 equivalent) once you dose 1 mL of that concentrate into 1 liter of finished brewing water. That relationship is what lets you hit a specific target number instead of eyeballing a pinch of powder into your kettle.
Dissolution is usually complete within a minute or two of stirring in room-temperature water, though warm water speeds it up if you are in a hurry. Cross-contamination is the main risk worth watching for: use separate spoons or syringes for each concentrate, and rinse any tool that touches one before it touches the other. A cloudy concentrate, an odd smell, or visible sediment after storage means the batch has degraded and should be discarded rather than used.
Pro Tip: Mix a fresh batch of both concentrates on the same day each month so you never have to guess how old a bottle is.
Three tested recipes with per-liter dosing and best uses
Three DIY recipes cover most of what home baristas need, each landing in a different part of the mineral spectrum. Barista Hustle’s standard recipe, Scott Rao’s espresso-leaning water, and a Third Wave Water clone all start from the same distilled base but diverge in how much hardness and alkalinity they add.
| Recipe | TDS (mg/L) | Hardness (mg/L) | Alkalinity (mg/L) | Best use |
|---|---|---|---|---|
| Barista Hustle | ~90 | 50 | 40 | Pour-over, light roasts |
| Rao water | ~110 | 70 | 40 | Espresso, immersion brewing |
| Third Wave Water clone | ~150 | 100 | 50 | Drip, cupping, fuller body |
Barista Hustle’s recipe sits at the gentle end of the range, and it is the one most pour-over brewers reach for first. Its moderate hardness and alkalinity leave delicate acidity intact rather than muting it, which suits light-roasted single origins where floral and citrus notes are the point. If you are brewing a washed Ethiopian or a bright Central American lot, this is the profile that gets out of the coffee’s way.
Rao water pushes hardness up while keeping alkalinity close to Barista Hustle’s number. That extra hardness gives espresso and immersion brews more extraction power to work with, which matters because espresso runs hotter, faster, and under pressure, conditions that pull more out of the grounds in less time. The result tends to read as fuller body and more resolved sweetness in shots that otherwise taste thin.
The Third Wave Water clone sits at the top of the table on both TDS and alkalinity, which is the same territory occupied by the commercial packets of Third Wave Water. Higher alkalinity buffers more acidity, so darker roasts and drip methods that already lean toward bitterness get a rounder, less sharp cup. Cupping tables also tend to favor this profile since it delivers a heavier mouthfeel that some tasters read as more “complete.”
Small tweaks to any of these three shift the cup in predictable directions. Adding a bit more magnesium concentrate without touching bicarbonate increases perceived sweetness and clarity without changing how buffered the acids feel. Adding bicarbonate alone, on the other hand, softens sharpness but can flatten a coffee that was bright on purpose, which is worth remembering before you nudge a light-roast pour-over toward the Third Wave Water clone’s numbers.
Scaling recipes for bigger batches and simpler measuring
Once you have picked a recipe, the next problem is making enough of it without weighing fractions of a gram every single day. The concentrate method solves this cleanly, since the same two bottles can dose water for a single cup or a full gallon.
- For a 1-liter batch, dose the appropriate milliliters of hardness and buffer concentrate according to your chosen recipe’s target numbers, then top off with distilled water to the 1-liter mark.
- For a 4-liter batch, multiply your 1-liter dosing by four and mix everything into a jug you have already labeled with the recipe name.
- For a 1-gallon batch (about 3.8 liters), use roughly 3.8 times your 1-liter dosing, rounding to the nearest 0.5 mL since finished water is more forgiving than concentrate mixing.
Concentrates themselves can also be scaled up in strength rather than volume, which is useful if your scale struggles with small numbers. Making a 1,000x or 10,000x concentrate, where you dissolve far more salt into the same liter of water, lets you dose in larger, easier-to-measure volumes while still landing on the same final mineral numbers in your brewing water.
Spoon measures are the least reliable fallback here. A “pinch” or “quarter teaspoon” of Epsom salt varies enormously depending on how tightly it is packed, which defeats the purpose of building water in the first place. If you are genuinely stuck without a scale, err on the side of less mineral rather than more, since under-mineralized water produces a flat cup while over-mineralized water can taste soapy or chalky, and the second mistake is harder to walk back.
A standard kitchen scale that reads to 1 gram works fine once you are dosing concentrate rather than raw salt, since the volumes involved are large enough to measure accurately even without a jeweler’s scale.
Adjusting recipes for brew method, roast, and taste
The three base recipes are starting points, not fixed answers, and most home baristas end up nudging one or two numbers after the first few brews. The rule of thumb is straightforward: lower alkalinity to let bright, acidic single origins shine through a filter, and raise hardness or alkalinity when you are working with espresso or darker roasts that need help balancing bitterness.
Diagnosing a cup tells you which lever to pull first:
- A sour, sharp cup usually needs more alkalinity, not less hardness, since bicarbonate is what buffers acid perception.
- A thin, watery cup usually needs more hardness, since magnesium and calcium are what give the coffee extraction power to draw sweetness and body out of the grounds.
- A muddy or bitter cup sometimes means you have overshot on both minerals, and dropping back toward the Barista Hustle numbers is a reasonable reset.
That comparison isolates which mineral is actually driving the change you are chasing, rather than guessing from a single brew.
It is worth remembering that water is one variable among several. Grind size, dose, and brew time interact with water chemistry rather than existing separately from it: a coffee that tastes sour on Barista Hustle water might need a finer grind before it needs a different recipe. Matching your brewing method to the coffee’s roast profile is worth sorting out before you start chasing water tweaks, since a mismatch there can mimic a water problem that does not actually exist.
Safety, machine care, and storage cautions
Building your own coffee water is safe when you stick to food-grade ingredients and basic hygiene, but a few habits protect both your health and your equipment. Always use unscented, food-grade Epsom salt and baking soda rather than bath-salt or cleaning-grade versions, since additives in those products are not meant for consumption.
A short list of practical cautions covers most of what can go wrong:
- Discard any concentrate that looks cloudy, smells off, or has visible sediment, since that signals contamination or incomplete dissolution rather than a usable batch.
- Descale machines on a regular schedule even when brewing with distilled water, since distilled water’s mineral-free nature makes it slightly more aggressive toward some machine components over long-term use.
- Favor magnesium-heavy recipes over calcium-heavy ones where you have a choice, since magnesium is less prone to forming the stubborn limescale that calcium leaves behind.
- Keep concentrates refrigerated and dated, and treat anything older than a few weeks as suspect rather than risking a stale batch in your next brew.
- Follow a regular equipment cleaning routine alongside your water routine, since mineral buildup and coffee oils both affect flavor independently of what is in your kettle. A step-by-step cleaning routine for your grinder and brewer closes the gap that water alone cannot fix.
None of this requires special equipment beyond what you already bought for mixing concentrates, but the habits matter more the longer you keep brewing with built water.
How Moustache Coffee Club pairs ultra-light roasts with water recipes
Ultra-light, Nordic-style roasting is built to preserve a coffee’s original acidity and origin character rather than roast over it, which makes water choice more visible in the cup than it would be with a darker roast. At Moustache Coffee Club, that roasting approach means the floral, citrus, or stone-fruit notes in a washed Ethiopian or a high-altitude Colombian lot are still front and center when the coffee reaches you, roasted to order and shipped the day it is roasted.
Because those flavors are the point, the water you brew with matters more, not less:
- Start with the Barista Hustle recipe on any ultra-light single origin, since its lower alkalinity leaves bright acidity intact instead of buffering it away.
- Save the Third Wave Water clone for darker or blended coffees, where its higher alkalinity rounds out flavors that ultra-light roasting is specifically trying to avoid muting.
- Treat the first cup as a baseline, then adjust hardness slightly upward if the coffee tastes thin rather than assuming the roast itself is at fault.
A coffee roasted to highlight origin character is also the easiest way to actually hear what a water recipe is doing, since there is less roast flavor masking the difference between one mineral profile and the next.
When DIY water is worth it and when it is not
Building your own coffee water is worth the effort if you are chasing a specific, repeatable flavor target and you brew often enough to justify keeping two labeled concentrates in the fridge. Home baristas dialing in a new single origin, or anyone frustrated that the same beans taste different depending on which faucet filled the kettle, get the most out of this.
If you brew occasionally, or your tap water already tastes clean and produces coffee you enjoy, commercial mineral packets or simply a good carbon filter on your tap may get you 90% of the benefit for a fraction of the fuss. There is no prize for tinkering past the point where the cup actually improves.
The readers who get the most out of this method are the ones who log what they change. Write down which concentrate you adjusted and by how much, then taste before changing anything else. Small, single-variable steps are what separate a real improvement from a lucky batch.
— Sean
Try your next water recipe with beans that show the difference
A water recipe only reveals itself when the coffee behind it has nothing to hide, which is exactly what ultra-light, Nordic-style roasting is built for. Single-origin coffee roasted to order and sent out the day it is roasted ensures the batch you use to test a new recipe is as fresh as it gets rather than weeks old by the time it reaches your kettle.
A simple test worth running: pick one origin from the subscription plans, brew it once with tap water and once with the Barista Hustle recipe from this article, and taste them side by side.
- Browse the current plans, including Duet and Custom, to find a single origin worth building water around.
- Send the Tasting Series or a gift subscription to someone who wants to run the same comparison.
- Start with one bag and treat it as your baseline before you commit to a full recipe.
Check the plans page to pick a coffee and get started.
Sources
A handful of references are worth bookmarking if you plan to keep tweaking your water over time.
- DIY Water Recipes Redux — Barista Hustle
- Water and coffee acidity: how to adapt your water for different extraction methods — SCA (2019)
- Perfectly mineralized water — SCA (2026)
FAQ
How do you make coffee water?
Start with distilled or reverse osmosis water, then add small doses of a magnesium sulfate concentrate for hardness and a sodium or potassium bicarbonate concentrate for buffering. Most home baristas prepare each mineral as a separate concentrate first, then dose both into the brewing water using a syringe for accuracy, following a tested recipe like Barista Hustle’s.
How much coffee for 8 ounces of water?
The right coffee-to-water ratio depends more on your brew method than on which water recipe you use, since built water changes extraction character rather than the base ratio. A general starting ratio for pour-over is worth checking against brew ratio fundamentals before adjusting for your specific water profile.
How much coffee should I use for 4 cups of water?
As with smaller batches, the coffee-to-water ratio for a 4-cup brew stays consistent regardless of which mineral recipe you are using, since water chemistry affects flavor extraction, not the baseline ratio. Check ratio guidance for brewing with water alone and scale it to your batch size.
How much coffee for a gallon of water?
For large batches, the same ratio principle scales up: multiply your standard cup-based ratio by the number of cups in a gallon rather than switching to a different formula. This holds whether you are brewing with tap water, distilled water, or a mineral-dosed recipe like the ones covered above.
What is the difference between Barista Hustle and Rao water recipes?
Barista Hustle’s recipe uses lower hardness and is built for pour-over and light roasts, while Rao water uses higher hardness at a similar alkalinity level, which suits espresso and immersion brewing better. Both start from the same distilled water base and differ mainly in how much magnesium sulfate concentrate is dosed.
