Water purification methods, such as reverse osmosis (RO) or distillation, remove nearly all dissolved solids and beneficial minerals. This results in exceptionally clean water, but it often has a flat, unappealing taste. Demineralized water is also aggressive, meaning it can leach materials from plumbing or appliances. Remineralization is the targeted process of reintroducing specific mineral salts back into this purified water to achieve a balanced profile for taste, health, and equipment longevity.
Essential Mineral Compounds for Remineralization
Achieving a balanced mineral profile requires more than simply adding standard table salt, which is primarily sodium chloride. Effective remineralization relies on a triad of salts that introduce calcium, magnesium, and bicarbonates into the water. These compounds are typically sourced as food-grade powders to ensure purity and solubility.
Magnesium sulfate (Epsom salt) is often used to introduce magnesium, which enhances the water’s texture or “mouthfeel.” Calcium chloride is the preferred source of calcium because it is highly soluble and contributes to the water’s general hardness (GH). These hardness minerals are crucial for flavor extraction, especially in brewing.
The third component is a buffer, typically potassium bicarbonate or sodium bicarbonate (baking soda), which introduces alkalinity. This alkalinity, measured as carbonate hardness (KH), prevents the water from being overly corrosive and helps stabilize the pH. The balance between these hardness and alkalinity components determines the final water quality.
Practical Ratios for Drinking Water and Specialized Uses
The goal for remineralized drinking water is to achieve a total dissolved solids (TDS) concentration between 50 and 150 parts per million (ppm). This range is considered optimal for both flavor and health benefits. A simple recipe involves first making two concentrated stock solutions that are then added to the purified water.
To create a master concentrate, dissolve specific amounts of food-grade salts into a small volume of purified water, such as one liter. A common preparation involves dissolving 2.45 grams of magnesium sulfate and 1.68 grams of sodium bicarbonate separately into one liter of water each. These “stock solutions” are highly concentrated, often representing a hardness (GH) or alkalinity (KH) of approximately 1000 ppm. For general drinking water, adding 5 to 10 milliliters of each concentrate to a full liter of purified water brings the TDS into the desired range.
For a more straightforward, household approach without a precise scale, a small pinch of Himalayan pink salt and a tiny pinch of Epsom salt can be added to a gallon of purified water. This method offers a rough estimation: Himalayan salt provides trace minerals and sodium for flavor, while Epsom salt boosts the magnesium. However, this lacks the precision required for specialized applications like coffee brewing.
Specialized uses, such as for espresso machines, demand an exact mineral balance to prevent scale buildup while maximizing flavor extraction. The Speciality Coffee Association recommends a general hardness (GH) of 50–110 ppm and a carbonate hardness (KH) of 40–70 ppm for high-quality coffee. Ratios must be carefully managed; a high concentration of calcium and bicarbonate will lead to rapid limescale formation on heating elements. Conversely, insufficient KH can result in a coffee flavor that is overly sharp or aggressive.
Measuring and Monitoring Mineral Levels
After adding the mineral salts, it is necessary to confirm the final concentration for taste and appliance safety. The most common tool for this is a total dissolved solids (TDS) meter, which measures the electrical conductivity of the water and converts it to a reading in parts per million (ppm).
A TDS reading of less than 50 ppm suggests the water will taste flat, while a reading above 500 ppm can indicate a high concentration of salts that may affect taste. For specialized applications, basic TDS measurement is often insufficient because it only provides a total number, not a breakdown of the specific ions.
Testing for General Hardness (GH) and Carbonate Hardness (KH) provides a deeper understanding of the water’s composition, which is particularly relevant for espresso machines. GH test kits measure the concentration of calcium and magnesium ions, while KH kits measure the buffering capacity provided by bicarbonates. Maintaining a GH of 50–70 ppm and a KH near 40–50 ppm is recommended for espresso to ensure good flavor and minimize scaling. Over-mineralization, or adding too much salt, ruins the taste and can lead to excessive scale formation in appliances, significantly reducing their lifespan and efficiency.