Water Remineralization Guide – The Rhyming Leaf

This guide owes much to the blogs of Tea Secrets / Empirical Tea. Please refer to their posts for a comparison with a slightly different approach.

NOTE THAT YOU ARE USING THIS GUIDE COMPLETELY AT YOUR OWN RISK. WE ACCEPT NO LIABILITY FOR THE POSSIBLE CONSEQUENCES OF INCORRECT, IRRESPONSIBLE, OR INCOMPETENT USE OF THE INFORMATION PROVIDED.

IT IS OF PARAMOUNT IMPORTANCE THAT ALL SALTS & COMPOUNDS THAT YOU ARE CONSUMING ARE PHARMA / FOOD GRADE CERTIFIED BY A TRUSTED AUTHORITY.

When remineralizing water, the first step is to carefully weigh the necessary amount for each salt. In this regard, I guarantee that the investment into a reliably accurate milligram scale will not feel unrewarding in the end, as quantities are so small that it may reveal quite a challenging task without the proper equipment. If you opt for a simpler consumer-grade scale, there are methods to improve its accuracy: please refer to the previously mentioned blogs for a lot of useful tips on how to use it. In any case, always keep your scale on a stable and level surface. Even if you have a stainless steel small weighing bowl, and if you try using your lab spatula, it is a little tricky to push all salts off into the vessels or containers of the next steps, without leaving a small amount on the bowl. Pushing powders with air does not always help in my experience. The trick I use, is to fold into a “V” shape a rectangular sheet of a very smooth material, to converge the powder down. It could simply be paper, or even better, a sheet of food grade plastic of the same shape, cut out for example, from some empty Mylar tea pouches you may have hanging around. As for the real letter “V”, place that in a way that the inclination of both sides is symmetrical and about 45° vertically from the weighing plate, so that the salts collect at the base. You will need something to act as a support, so that the “V” does not bend, nor tip over. I use a small piece of a plastic corner guard and some adhesive silicone bump protectors on the bottom on both sides. Be creative. You can then push all salts onto their target quite easily and consistently with a flat spatula.

I am using this weird-looking contraption. With little effort you can create something similar, or much better.

Approaching the task of making remineralized water, you mainly have three options. The first is of course, to drop the powders in the tank full of purified water directly and hope they dissolve completely. But weighing the salts can be a little cumbersome and time-consuming operation at times. Hence, especially if you plan to make this a regular thing, my advice is to stock up with pre-weighed recipes that you can store inside resealable glass jars or bottles. There are two methods: you can store your minerals dry, or you can create a concentrated solution with them. The latter, is to say that you can dissolve pre-emptively your salts into purified water (directly, of by creating some useful intermediaries called single-salt solutions: see below), and store them in that form. When time comes, simply pour that concentrated solution into your full tank and instantly have your remineralized water ready for brewing. I shall return to this second approach in a moment. In both cases, it is important to decide in advance how large your water batches are going to be, that is to say how many litres / gallons of water you are going to produce every single time, so that you can calculate accordingly the weight of the salts for each recipe.

To store your pre-mixed minerals dry is by far the easiest method. Please note however that this method is only suitable for salts that have a good solubility (more than 80 g/L), therefore not applicable for recipes that contain e.g., gypsum [CaSO₄·₂ʜ₂ᴏ], calcium carbonate [CaCO₃] or magnesium carbonate [MgCO₃]. To achieve this, carefully pour the weighed powders, one by one, into a small glass container, then add some silica-gel Tyvek™ sachets and accurately seal the jar. That is it. And that is how I used to store minerals when I started to experiment with water remineralization. Even if you used many sachets, when you will open the jar after some time has passed, due to residual moisture some of those salts will probably have aggregated into larger formations, or they will be stuck to the bottom of the glass container. That is not a problem: just scrape them delicately with your lab spatula. Simply be careful not to apply too much pressure, as they could bolt out of the jar and you may end up significantly altering the recipe.

When the moment comes to actually remineralize the water, however, I strongly recommend not to drop the salts directly into the full tank. Salts are sold in many shapes, from fine powder up to tiny uneven little crystals of around 1-2 mm diameter. The latter forms can precipitate quite easily. Beside, even if stored carefully, most crystals tend to stick together forming larger aggregates, that take much longer to properly dissolve. As I wrote, if you store different dry salts together in a jar, even a little residual moisture can aggregate them into harder and more complex formations that resist thorough dissolution.

That is why, before pouring the stored-dry minerals in water, I recommend dropping them in a stainless steel mortar, and grinding them delicately with the pestle into a fine and even powder. Leaving the pestle in to avoid losing some residue stuck to the bottom of it, then you can add a small amount of purified water directly inside the mortar. You will obtain a milky white, very concentrated solution. You can keep mixing the solution and crush any leftover aggregate, then quickly fill the mortar up about 2/3 of its capacity, stir it a bit, and pour the resulting solution into your large water tank (already full with the right amount of purified water). A key factor to this method is time: try to be careful, but not too slow. After this, to make sure no residue remains in the mortar, with a glass pipette, a syringe or a beaker, you can collect some more water from the tank and fill the mortar up twice, each one pouring the water back. Please do not forget to do the same thing for the glass container that held the salts initially, as some residue will be there as well.

Grinding the stored-dry salts will be useful to cut down on the time required for adding the powders to the purified water, therefore making the process a little less cumbersome. It is however important to wait after that, for minerals to properly dissolve. The absence of any large crystal will help in that regard as well, time-wise. I recommend holding up for at least an hour before bottling or brewing, and to agitate or stir the water from time to time. ^{(see notes at the bottom of the page)}

unground crystallized salts, after a small storage period

The method I highly recommend, nonetheless, is to store weighed salts as a concentrated solution. You can add an extra, but very useful step, by storing them separately as single-salt solutions – we will discuss this later on – or you can mix them from the beginning and then store the mixed concentrate in a relatively-small glass container. Please keep in mind that mixing them together is again not suitable for recipes containing calcium carbonate [CaCO₃] or magnesium carbonate [MgCO₃]. As the most soluble salts will have plenty of time to thoroughly dissolve during the longer storage period, for this method you do not need to grind them first. However, I do recommend to add one salt at a time, and to wait until at least you see no visible particulate in suspension when inspecting the water, before adding the next. You may want to stir or agitate the water often, while waiting. When choosing the capacity (size) of the glass container to store the concentrated solution in, please pay close attention to the solubility^1-11 of the salts that you are using – to avoid precipitation over time and the creation of a sediment on the bottom of the bottle or jar. The Water Recipe Calculator will be an essential aid in this regard – as a reference, and for simplifying the calculations: for each mineral I list the solubility, but most importantly, the recommended concentration. For convenience, you can find a pre-filled calculator for each one of my recipes on their pages.

The values for solubility equilibrium are temperature-dependent: I also list them below, mostly for 20° C. Simply put, you need to make sure there is relatively enough water (and in some case, the proper conditions) for all salts to perfectly dissolve. Generally speaking: the more water, the better. The dissolution of most salts is an endothermic reaction, thus increasing the temperature of the water could theoretically speed things up. But I would rather recommend to avoid heating up the container, as a warm solution may promote the proliferation of microorganisms. That being said, keep in mind that a few minerals, like calcium sulfate CaSO₄ ^(anhydrous), CaCO₃, or MgCO₃, exhibit instead retrograde solubility, thus their dissolution reaction is exothermic. In this case, the inverse principle applies: cooling the solution will help. To achieve this – as the last step, when all other salts have completely dissolved – you could let the container rest in the fridge for a while, adding CaSO₄ ^(anhydrous) when it is cold and waiting again until complete dissolution occurs (it may take days: agitate the water often if you can; CaCO₃ and MgCO₃ also require CO₂ acidification: see below). To really understand how it works, you need to experiment a little. The golden rule is: if precipitation does occur over time, please either wait a little more between each addition; depending on the salt: cool, or acidify the water (see below); or find a larger glass container.^1-12

If you plan to store those solutions for a long time, I recommend buying an UV disinfectant apparatus, large enough that it can fit your glass containers inside. This is not essential, but if you do, please make sure the jars or bottles are of good quality glass and made for food storage, and that the UV machine is safe to use, as it may be dangerous if of poor quality (e.g. it may produce ozone). There is no need to sterilize the dry salts: please do not try, especially if there are silica-gel sachets inside the jar.

The method I currently use to remineralize water, consists in creating at first many intermediaries I call single-salt solutions. That is to say, storing a large amount of a separate concentrated solution (at least 1 litre) for every single salt that I make use of in my recipes, with a convenient concentration (recommended concentrations are again listed in the Water Recipe Calculator). This way, I save quite a lot of time when I need to add minerals to my water tank, or when I need to create many pre-mixed concentrates of a recipe. Having all the single-salt solutions means that effectively, you may quickly measure the required amounts in millilitres with a glass pipette, a syringe or a beaker (use the same tool to easily calculate how much you need), and pour the solution either into the container for the pre-mixed concentrate – remember to at least double the total amount of concentrates you used (recipe total millilitres) by adding more purified water, to prevent precipitation over time – or directly into the full water tank for immediate use. As salts are already completely dissolved, there is no need to wait in-between each addition: the whole operation takes under a minute.

Due to difference in solubility, if for gypsum [CaSO₄·₂ʜ₂ᴏ] you can only create a solution up to about 1 g/L of concentration, for Epsom salt [MgSO₄·₇ʜ₂ᴏ] you could instead theoretically even go as high as 1100 g/L. You might prefer however, never to exceed 20 g/L for an easier dosage. There are some salts that – even if highly soluble – are more practical to be dosed, when stored as highly-diluted solutions. For example, I use potassium bicarbonate [KHCO₃] in such small amounts, that it would be quite complicated to dose even a 10 g/L solution of that salt (or even more, to weigh the required dry powder). In that case, I recommend creating a more diluted 3 to 6 g/L solution as an intermediary. Other solutions that are needed in my recipes are sold as such, like sodium chloride [NaCI], sodium silicate [Na₂SiO₃·ₓʜ₂ᴏ], dissolved amorphous silica [H₄SiO₄], and hydrochloric acid [HCl]. For NaCI, it is convenient to use widely-available saline solution of irrigation or inhalation grade for matters of purity, and because common kitchen’s salt often contains additives that would impede thorough dissolution. The dissolved compound of amorphous SiO₂ is called orthosilicic acid [H₄SiO₄]: when you read “SiO₂” or “silica” on a mineral water label, that is the compound they are actually referring to. However, its solubility is very low, around 113 mg/L. Avoid of course using any crystalline silica. Also, please do not use colloidal silica, as those silicate polymers are quite insoluble, and do not try to dissolve amorphous silica powder yourself, as it would take a very long time.^10-12 Special reference need to be made about solutions of sodium silicate [Na₂SiO₃·ₓʜ₂ᴏ]: see below for more information. In regard to hydrochloric acid [HCl], please do not use solutions more concentrated than 5%, and in any case, exercise caution and wear protection while handling them. Besides, please do not exceed the recommended dosage, as you may end up completely depleting the alkalinity buffer of your recipe.

If you own a solution with a concentration expressed as a percentage, to convert that concentration in g/L you need to multiply it by 10 (e.g. 3% = 30 g/L). Should you only know the concentration of your solution as expressed in parts-per-million (ppm), divide that number by 1000 to obtain the concentration in grams per litre (24000 ppm becomes 24 g/L): 1 ppm equals 1 mg/L. Paying attention not to exceed the recommended limits, you could try to play a bit with the numbers, in order to create a solution with a concentration compatible with the requirements of your recipes, with the capacity of your pipettes or syringes or beakers and with the size of your water tank.

You could also hasten the dissolution of most minerals by altering the pH of the water, making it more acidic, or in some cases more alkaline. The easier way to acidify would be to add abundant amounts of carbon dioxide [CO₂], using a water carbonator like SodaStream™. That is especially important for calcium carbonate [CaCO₃] and magnesium carbonate [MgCO₃], as the only way to make the insoluble carbonates [CO₃^—] dissolve, is to have them react with CO₂ to form the soluble bicarbonates [HCO₃^–].^8-9

A separate discussion deserves sodium silicate [Na₂SiO₃·ₓʜ₂ᴏ], that will need both alkalinization and acidification to be used. Using this compound in your recipes provides a smart way to introduce monomeric dissolved amorphous silica – also known as orthosilicic acid [H₄SiO₄] – into your remineralized brewing water. However, achieving that requires a little work. You can find sodium silicate commercially sold as either a solid compound (fine powder / crystals / beads), or as a liquid solution; both can have various Na₂O – SiO₂ mass ratios or concentrations. Although it is dangerous to handle, a liquid solution must be preferred in order to simplify the process. Please only purchase a solid sodium silicate compound if the weight ratio of SiO₂ is at least 3 times higher than that of Na₂O (e.g. 60% SiO₂, 20% Na₂O): this is sometimes sold as low-alkalinity sodium silicate. Either way, in order to create a convenient monomeric-H₄SiO₄-saturated single-salt solution of sodium silicate, you need to create a solution with a SiO₂ concentration of 124 mg/L. Please use the Water Recipe Calculator to obtain the right value. Please also see below for the correct procedure to thoroughly dissolve solid Na₂SiO₃·ₓʜ₂ᴏ compounds, as it is quite complex. Ultimately, for both solid and liquid products, heating is required to dramatically raise silica solubility, followed by a last step of dilution – to achieve the recommended concentration – and neutralisation (acidification), to obtain a solution with a pH that falls within the range of drinking water values. The simplest way to achieve both goals, is by making the hot sodium silicate solution react with an abundant quantity of CO₂-rich purified water (credits to Max of the teasecrets blog for this method).^10-13 Skin contact with a strongly basic solution can cause serious chemical burns. Exposure to sodium silicate fumes can be irritating for the respiratory tract. Always wear skin, eyes, and breathing protection while handling sodium silicate compounds in concentrated, non-neutralized forms.

It may all sound quite complicated at first, but using single-salt solutions will save you a lot of time if you produce remineralized water regularly and, if done correctly, should help you avoiding the issue of precipitation completely.^1-12

Finally, I cannot stress this enough: pay much attention to the storage of your salts and tools, for sanitary, practical, & economical reasons.

You only need less than half a gram of each salt per batch of water prepared, and salts usually comes in bags of 200 g up to 1 kg. It goes without saying, that you do not want to open those bags and let moisture in every time. I recommend using some small glass jars – similar to the ones I am showing in the examples below – to store 50 or 100 grams of salt per time, together with at least one Tyvek™ silica-gel bag of 5 g. Fill the original containers of the salts up with silica-gel sachets and seal it carefully (consider incepting 2-3 more ziplocks for minimizing moisture intake, or storing them in an airtight food storage container like the ones in the examples, containing larger-size silica-gel sachets).

As a last note, in case you are wondering, I do not get paid by any of the brands of the sample products I recommend. They are just the best examples I could find on Amazon and on some other shops, for each country I looked for. If you prefer not buying from Amazon, you can try looking for the same products elsewhere, but at least you will have some names to start with for your query. I tried only few of them, so also feel free to look for other brands and products. But please make sure that what you find is reliably food-quality certified. Do not poison yourself slowly with products that are not made for human consumption and contain traces of unhealthy other compounds. I shall say more: do not even trust the examples I provide you with: double-check them extensively and, if you are not sure about their certifications or quality, please keep looking elsewhere for a better product. I did my best, but I am fallible like everyone else.

For a step-by-step review of the different methods previously proposed, please refer to the following guides. The recommended method is the last one.

How to mix the dry salts of a recipe for long-term storage (easier method, not suitable for recipes containing CaSO₄, gypsum, CaCO₃, MgCO₃, or sodium silicate):

Decide in advance how much water you are going to produce (it should depend on the capacity of your water tank). Using the Water Recipe Calculator, for each salt required by the recipe, input its concentration in milligrams per litre or US gallon, and then the number of litres or gallons that you plan to produce into the red cell. You will obtain the total amounts. For convenience, you can find a pre-filled calculator for each one of my recipes on their pages.
One by one, carefully weigh each salt powder and drop it / push it thoroughly into a small sealable glass container that was made to store food.
Do not include, of course, those minerals that you own as solutions, like saline [NaCl], or amorphous silica [SiO₂] (dissolved as orthosilicic acid [H₄SiO₄]).
Add some Tyvek™ silica-gel sachets, of a format compatible with the size of the glass jar.
Seal the jar tightly and store it in a clean and dry place, away from direct sunlight.

How to produce remineralized water using the previously stored-dry, pre-mixed salts:

Carefully open the sealed glass container, paying attention not to spill some of its contents.
Pour the salts into a stainless steel mortar. Some crystals may have adhered to the bottom of the container due to absorbing residual moisture: in that case, helping yourself with your lab spatula, delicately scrape them off. Please be careful not to apply too much pressure, as they could bolt out of the jar. Do not worry if some fine sediment is left (see №8).
Delicately grind the salts in the mortar with the pestle into a fine and even powder.
Leaving the pestle inside the mortar, with a glass pipette or syringe or with a beaker, pour some purified water on top of the powder, then carefully stir the solution and crush all eventually formed lumps. Time is an essential parameter for this and the next steps, but try not to spill anything out of the mortar.
Further add water to fill up about 2/3 of the mortar capacity and keep stirring and breaking any aggregate that may form. You will obtain a turbid homogeneous solution.
Quickly pour the solution back into the water tank (full with the right amount of water you previously planned to produce).
With a glass pipette, a syringe or a beaker, collect some more water from the tank and fill the mortar up almost to the edge for two or more times, each one pouring the water back, to make sure no residue remains there.
Do the same procedure with the glass jar that initially contained the salts, as some sediment may be left there as well, and wait for it to dissolve. You may hasten the process by stirring and scraping delicately with a lab spatula or by shaking the sealed container.
Wait for an hour for the salts to completely dissolve.
If your recipe includes minerals that you own as solutions – like saline [NaCl], or dissolved amorphous silica [SiO₂] (i.e. orthosilicic acid [H₄SiO₄]) – you need to add those at the end with a glass pipette, a syringe or a beaker, directly into the tank.

How to create a concentrated solution of a recipe, for long-term storage (not suitable for recipes containing CaCO₃, MgCO₃, or sodium silicate):

Find a large enough clear glass container, sealable and liquid-foods suited. The capacity (size) of the container depends on the total amount of all concentrated solutions needed to produce a specific quantity of water using a certain recipe. You can easily calculate that value (recipe total millilitres) using the Water Recipe Calculator. To obtain it, for each required salt, input its concentration in milligrams per litre or gallon and the highest recommended concentration of its single-salt solution. Afterwards, input the number of litres or gallons that you plan to produce into the red cell. Multiply the calculated recipe total millilitres by at least 1.5, to get an estimate of the ideal capacity a clear glass container should have to store the concentrated recipe properly, avoiding precipitation over time. For convenience, you can find a pre-filled calculator for each one of my recipes on their pages.
Once you have it, fill the glass container for about 2/3 of its capacity with purified water.
Now you need to weigh the powdered salts. However, note that if your recipe includes anhydrous calcium sulfate [CaSO₄], you may want to add that for last: see №7.
Carefully weigh the first dry salt powder of your recipe and drop it in the water inside the glass container.
Delicately stir or agitate the solution and wait until the salt has dissolved completely (no particulate in suspension should be visible when inspecting the water).
Repeat steps 4 and 5 for every other salt of the recipe.
If your recipe includes anhydrous calcium sulfate [CaSO₄], when all other salts have completely dissolved – you could let the glass container rest in the fridge for a while, only adding CaSO₄ when the water is cold. Then put it in the fridge again and wait until complete dissolution occurs (it can unfortunately take a long time).
If your recipe includes minerals that you own as solutions – like saline [NaCl], or dissolved amorphous silica [SiO₂] (i.e. orthosilicic acid [H₄SiO₄]), or hydrochloric acid [HCl] – you can add those as well, at the end, with a glass pipette, a syringe or a beaker.
When all the salts are in the solution, fill the rest of the glass container with purified water leaving a 5-10% empty margin from the edge and seal it carefully.
If done correctly, no deposit should form over time on the bottom of the container. If a deposit should indeed form, find a larger container.
For long term storage, we recommend sterilizing the solution with a UV disinfectant apparatus large enough to fit the glass container inside.

Recommended method. How to use single-salt solutions to make concentrates for long-term storage, or to directly produce remineralized water:

Procure yourself some large clear glass containers (with a capacity of at least 1 litre), one for every salt that you make use of in your recipes.
In order to create a separate solution for each salt, with a specific concentration, you will need to measure a precise amount of purified water to fill the containers, and then add an exact weight of powdered mineral to the water. The recommended concentrations are listed in the Water Recipe Calculator.

Please remember that to obtain a correct concentration, you have to subtract the chosen weight of the salt from the amount of water you are going to measure. For the sake of simplicity, we shall assume that 1 millilitre of water weighs 1 gram. Let’s say you need to create a 20 g/L solution: subtract that amount from 1000 g of water. Therefore, you would need to measure 20 g of salt, and 980 mL of water. Of course, depending from the precision of the measuring tools at our disposal, it could prove impractical to measure the correct amount of water for solutions with a concentration of less than 10 g/L: in that case, simply measure 1 litre.
When it comes to attainable concentrations, you can unfortunately only create a solution up to 1 g/L of concentration for gypsum [CaSO₄·2H₂O], and calcium carbonate [CaCO₃]. The good news is that for Epsom [MgSO₄·7H₂O] and most other common salts, you can instead create cosy 5 – 10 g/L solutions that will last longer and are easy to dose. Paying attention not to exceed the recommended limits, you may however try to play a bit with these numbers, in order to create a solution with a concentration compatible with the requirements of your recipes, with the capacity of your pipettes / syringes / beakers and with the size of your water tank (we recommend tanks having a capacity of at least 10 litres). Depending on the salt, to obtain complete dissolution, you may need to wait from a few minutes to a few days, shaking the container vigorously or stirring the solution from time to time.
If you buy a mineral that is already commercialized as a single-salt solution, you may normally keep it and dose it as it is. However, if is concentrated enough that it may prove unpractical to dose it, then you may need to dilute it using purified water until you achieve the recommended concentration. Use this to help with the calculations.

To create a single-salt solution of anhydrous calcium sulfate [CaSO₄], you need to refrigerate the water first, then add 1 g/L of salt, and finally keep the solution in the fridge until you achieve a complete dissolution.
Creating a single-salt solution of CaCO₃ or MgCO₃ may prove challenging, as those salts have an extremely low solubility under normal conditions: again you need to refrigerate the water first, carbonate it heavily when it is cold, then add the salts and store the solution in the fridge for 12 hours. Finally, carbonate the solution again, paying attention not to spill any of it, and store it in the fridge. This should allow for the insoluble carbonates to convert into soluble bicarbonates, and the cold should prevent any precipitation to occur over time.
Creating a single-salt solution of sodium silicate [Na₂SiO₃·ₓʜ₂ᴏ] is even more complex. You can find sodium silicate commercially sold as either a solid compound (fine powder / crystals / beads), or as a liquid solution; both can have various Na₂O – SiO₂ mass ratios or concentrations. Although it is dangerous to handle, a liquid solution must be preferred in order to simplify the process. Please only purchase a solid sodium silicate compound if the weight ratio of SiO₂ is at least 3 times higher than that of Na₂O (e.g. 60% SiO₂, 20% Na₂O): this is sometimes sold as low-alkalinity sodium silicate.
In order to create a convenient and effective monomeric-H₄SiO₄-saturated single-salt solution of sodium silicate, you need to obtain a SiO₂ concentration of 124 mg/L. Please use the the Water Recipe Calculator to calculate the correct concentration for the commercial sodium silicate product you own, by inputting the percentage values for its mass ratios or concentrations of Na₂O and SiO₂.
Should you decide to buy a low-alkalinity solid sodium silicate compound (e.g. powdered), to dissolve it you need a large HDPE water container with a capacity of at least 3 litres, and a carbonator. First, decide the volume of concentrated solution you are going to produce, and carbonate heavily that same amount of purified water, storing it into the HDPE container. Then, please multiply the recommended weight per litre of your solid compound by the volume of your water container in litres (e.g. 0.2 g/L * 3 litres = 600 mg). Then, multiply 10 ml for the same number (e.g. 10 ml * 3 = 30 ml). Now, you need to dissolve the calculated amount of solid compound into the calculated amount of purified water (e.g. dissolve 600 mg in 30 ml of purified water). Then, you need to increase the solubility of silica and force it to dissolve, by temporarily raising the temperature of the solution. For this you need a microwave oven and a small high quality borosilicate glass beaker. Heat the solution in the oven until it is boiling and then keep it boiling for another 30 seconds. Please be extra careful, as you will obtain a very hot and caustic solution. As a last step, dilution, to achieve the recommended concentration, and neutralisation (acidification) of the pH are required. The simplest way to achieve both goals, is by immediately pouring the heated solution into the HDPE container filled with the previously carbonated purified water (e.g. pour the 30 ml hot solution into the container previously filled with ∼3 litres of carbonated purified water).¹³
Should you instead purchase sodium silicate as a liquid solution, the procedure is simpler, but fairly similar. Again, you need an HDPE water container with a capacity of at least 1 litre, and a carbonator. First, decide the volume of concentrated solution you are going to produce, and carbonate heavily that same amount of purified water, storing it into the HDPE container. Then, carefully pour the exact calculated volume of product required for your concentrated solution into a small high quality borosilicate glass beaker. Using a microwave oven, heat the solution until it is boiling and then keep it boiling for another 30 seconds. Please be extra careful, as you will obtain a very hot and caustic solution. Again, as a last step, dilution and neutralisation of the pH are required. To achieve both goals, immediately pour the solution into the HDPE container filled with the previously carbonated purified water.
Skin contact with a strongly basic solution can cause serious chemical burns. Exposure to sodium silicate fumes can be irritating for the respiratory tract. Always wear skin, eyes, and breathing protection while handling sodium silicate compounds in concentrated, non-neutralized forms.
Credits to Max of the teasecrets blog for the CO₂ neutralization method.

TO PRODUCE PRE-MIXED CONCENTRATES FOR LONG-TERM STORAGE:

Once all the salts are dissolved into separate solutions, using the same Google Sheets document, you can calculate the total amount of all concentrated solutions needed to produce a specific quantity of water using a certain recipe (recipe total millilitres). To obtain that value, for each required salt, input its concentration in milligrams per litre or gallon and the concentration of its single-salt solution. Afterwards, input the number of litres or gallons that you plan to produce into the red cell. Multiply the recipe total millilitres by at least 2, to get an estimate of the ideal capacity a clear glass container should have to store the concentrated recipe properly, avoiding precipitation over time. For convenience, you can find a pre-filled calculator for each one of my recipes on their pages.
With a glass pipette, a syringe or a beaker, drop the calculated total amount for each concentrated single-salt solution inside the glass container.
When all the salts are in the solution, fill the rest of the glass container with purified water leaving a 5-10% empty margin from the edge.
Seal the container carefully. If you have it, sterilize the solution with a UV disinfectant apparatus large enough to fit the glass container inside. Then store it in a clean and dry place, away from direct sunlight.
If done correctly, no deposit should form over time on the bottom of the container. If a deposit should indeed form, find a larger container.

Finally, when you need to remineralize your ready-for-brewing water, simply pour the contents of the glass container into the full tank and wait 30 seconds for diffusion forces to do their job.

ALTERNATIVE USE: DIRECTLY PRODUCE SOME READY-FOR-BREWING REMINERALIZED WATER:

Measuring single-salt solutions is quick and easy enough that, alternatively, you could use this method to add the calculated total amount for each salt directly to the tank, every time you need to make a batch of remineralized water. This way, you would only need to store the single-salt solutions.

RECOMMENDED TOOLS (examples only, for Germany)

Water purification medium: I recommend installing at home a Reverse Osmosis [RO] system
- alternative: find a reliable vendor of certified double-distilled water or certified RO highly purified water
- alternative: ZeroWater 5 litre pitcher (replacement cartridges), it is convenient only if your tap water has <200 ppm TDS
- alternative: any kind of filtration that guarantees ≥99,8% purified water
Capacious water containers for mineralization of larger batches:
Weighing scale accurate to 0.001 grams (much better alternative)
Silica-gel in Tyvek™ bags 5 g (1 g) (for preserving compounds and tools dry)
TDS metre (manufacturer website) (measured TDS value is an approximation, as it is estimated from Electrical Conductivity)
pH metre (manufacturer website, better alternative, calibration solutions). Alternative tools: pH drops, pH strips
Lab spoon and spatula (for powders)
Glass pipettes, glass syringe (alternative), glass beakers (to measure and dose solutions)
Airtight food storage container, 16 L (21 L) (for storing compounds and tools)
30 ml glass jars (for storing dry salts as pre-mixed recipes, together with 1 g silica gel packs)
Stainless steel mortar & pestle (to promote full dissolution of stored-dry salts)
106 ml glass jars (72 ml, 150 ml, 250 ml) (for storing recipes as concentrated solutions)
1 litre glass bottles (1 litre alternative, 750 ml) (for storing single-salt solutions)
SodaStream carbonator (especially useful for recipes containing CaCO₃ or MgCO₃)
UV-C disinfectant apparatus (alternative, alternative, alternative) (useful for storing diluted mixtures for prolonged periods)
Protective gear for eyes, hands and for breathing (recommended)

SALTS & COMPOUNDS ^¹⁻¹¹

CAUTION: CONCENTRATED HYDROCHLORIC ACID IS A DANGEROUS SUBSTANCE. PLEASE AVOID CONCENTRATIONS HIGHER THAN 5%, USE IT RESPONSIBLY AND ALWAYS WEAR SKIN, EYES, AND BREATHING PROTECTION WHILE HANDLING IT IN UNDILUTED FORM.

CAUTION: CONCENTRATED SODIUM SILICATE IS A DANGEROUS SUBSTANCE. PLEASE USE IT RESPONSIBLY AND ALWAYS WEAR SKIN, EYES, AND BREATHING PROTECTION WHILE HANDLING IT IN UNDISSOLVED OR UNDILUTED OR NOT-NEUTRALISED FORMS.

IT IS OF PARAMOUNT IMPORTANCE THAT ALL SALTS & COMPOUNDS THAT YOU ARE CONSUMING ARE PHARMA / FOOD GRADE CERTIFIED BY A TRUSTED AUTHORITY.

Calcium sulfate [CaSO₄]
pH neutral
Anhydrous: sparingly soluble, retrograde solubility, ~2 g / L at 10°C
Gypsum, dihydrate [CaSO₄·₂ʜ₂ᴏ]: sparingly soluble, 2,14 g / L at 20°C

Calcium chloride [CaCl₂]
pH neutral
Soluble, 745 g / L at 20°C

Calcium carbonate^4-5 [CaCO₃]
ALKALINE, 20 mg/L pH 7.78¹⁴
Insoluble, retrograde solubility, ~0,01 g / L at 10°C
CaCO₃ reacts with water that is saturated with CO₂ to form Ca(HCO₃)₂, that is soluble

Magnesium sulfate [MgSO₄]
pH neutral
Epsom salt, heptahydrate [MgSO₄·₇ʜ₂ᴏ]: soluble, 1130 g / L at 20°C

Magnesium chloride [MgCl₂]
pH neutral
Bischofite, hexahydrate [MgCl₂·₆ʜ₂ᴏ]: soluble, 2350 g / L at 20°C

Magnesium carbonate [MgCO₃]
ALKALINE, 20 mg/L pH 7.86¹⁴
Sparingly soluble, retrograde solubility, ~0,1 g / L at 10°C
MgCO₃ reacts with water that is saturated with CO₂ to form Mg(HCO₃)₂, that is soluble

Sodium sulfate [Na₂SO₄]
pH neutral
Anhydrous: soluble, 195 g / L at 20°C
Glauber’s salt, decahydrate [Na₂SO₄·₁₀ʜ₂ᴏ]: soluble, 435 g / L at 20°C

Sodium chloride [NaCl]
pH neutral
Soluble, 358,9 g / L at 20°C

Sodium bicarbonate [NaHCO₃]
ALKALINE, 20 mg/L pH 7.56¹⁴
Soluble, 96 g / L at 20°C

Sodium silicate [Na₂SiO₃·ₓʜ₂ᴏ]
ALKALINE, 20 mg/L pH 7.70¹⁴
Soluble, ≥ 210 g / L at 20°C

Potassium chloride [KCl]
pH neutral
Soluble, 342 g / L at 20°C

Potassium bicarbonate [KHCO₃]
ALKALINE, 20 mg/L pH 7.49¹⁴
soluble, 337 g / L at 20°C

Silica [SiO₂], amorphous and dissolved as orthosilicic acid¹⁰^-12 [H₄SiO₄]
Weakly acidic: in an open CO₂ system, dissolved silica hardly influences pH

Hydrochloric acid [HCl]
ACIDIC, 20 mg/L pH 3.27¹⁴

Citric acid [C₆H₈O₇]
ACIDIC, 20 mg/L pH 3.98¹⁴

For a review of the contributions of single ions and common salts to the taste of tea, you can start by referring at the following pages. As perception of taste and smell is utterly subjective, I recommend however further personal experimentation on the subject: take part in the debate!

Water Guide – Tea Secrets

Truth Serum recipe – Empirical Tea

Water recipe – Tea Curious

EXAMPLES OF COMMERCIAL SALTS, BY COUNTRY

IT IS OF PARAMOUNT IMPORTANCE THAT ALL SALTS & COMPOUNDS THAT YOU ARE CONSUMING ARE PHARMA / FOOD GRADE CERTIFIED BY A TRUSTED AUTHORITY.

PROVIDED LINKS TO PRODUCTS ARE EXAMPLES ONLY. WE HAVE NOT TRIED THEM ALL AND WE CANNOT GUARANTEE ABOUT THEIR QUALITY, NOR ABOUT THEIR SUITABILITY FOR THE INTENDED PURPOSE. DO NOT EXCEED SUGGESTED QUANTITIES.

The Sant’Anna™ Revisited recipes

Inspired by the tea-caring clarity of Italian high-altitude alpine springs, like Sant’Anna (Vinadio), Lurisia (M. Pigna), Sorgente Alba (Piccole Dolomiti), Pura di roccia (Valle dell’Elvo), Levico (Valsugana), Valverde (M. Rosa), and Etrusca (upper Val Bormida).

Sant’Anna™ Revisited №1: Shòu Jīn Tǐ 瘦金體 – PREVIEW

Sant’Anna™ Revisited №2: Qì Yǔ Lǐ 氣與理 – PREVIEW

About the pH of the recipes

Most of the alpine waters my recipes are based on have a pH ranging from 6 to 7. This is mostly due to their contents of composite carbonic acid [CO₂^(aq) & H₂CO₃], that is a convenient way to think about carbon dioxide in an aqueous system. On the other hand, today alkaline water is all the hype. A basic pH – chiefly provided by higher HCO₃^– concentrations – may perhaps be beneficial in helping to balance extraction on recipes with a higher TDS, and will strengthen tactile sensations, i.e. the body of tea. But in my opinion, the combination of a low TDS and a low concentration of bicarbonates, is one of the main factors that make many high-altitude alpine waters so ideal for tea. A slightly acidic pH will moderately improve the extraction of tea, and even more its flavour, by making it brighter and clearer. On the other hand, too much alkalinity will have a muting and dulling effect, especially on the retronasal aromas. Furthermore, polyphenols seem to be more stable in an acidic environment.^15-18

The simplest way to permanently lower the pH of your recipe would be introducing in the solution a small amount (<20 mg/L) of food-grade citric acid [C₆H₈O₇]. However, it must be noticed that citric acid creates much speciation and complexation of the dissolved compounds, modifying many characteristics of the water. A perhaps better approach could be using very low amounts of simpler and stronger acids, e.g. a few drops of a very diluted solution (<5%) of hydrochloric acid [HCl]. It must be noted that strong acids are very reactive substances and therefore potentially dangerous to handle. Also, an excessive acidification of the water, if not balanced, will have a negative impact as well on the taste of tea, making it sour and grassy: be sure never to deplete the alkalinity buffer. Yet another alternative approach could be trying to replicate the natural mechanism responsible for the acidity in mineral waters, i.e. by incorporating a high amount of CO₂ into the water. Achieving this, it would require a water carbonator like SodaStream™. The advantages of this method are that it simulates the natural composition of mineral water, that it will not create speciation and complexation like citrates, and that it is does not need to be handled or dosed as carefully as HCl. The disadvantage may be that you will lose most of that CO₂ when you will heat your water, so the effect will be reduced and less stable.

Please also keep in mind that in an open system – that is to say in a common situation where water can exchange CO₂ with the air – the Dissolved Inorganic Carbon, i.e. the sum of the carbonate species (C_T = [CO₂] + [HCO₃^–] + [CO₃^—] + carbonate complexes) is not a conserved quantity. DIC will decrease substantially in an acidic environment. In fact, as there is an equilibrium among the species in the carbonate system that depends on the pH, this value will ultimately determines the actual amount of carbonates and bicarbonates (and their complexes) present in the solution. At normal drinking water pH values, the concentration of carbonates will be quite low and bicarbonates will compose most of the DIC.^19-21 If you wish to reliably calculate the theoretical pH of a recipe, and the final concentration of HCO₃^–, we recommend using a proper hydrochemistry application like Aqion.

Another note has to be made about dissolved silica, i.e. orthosilicic acid [H₄SiO₄]. At a pH <9, solubility of monomeric H₄SiO₄ is low but constant (around 124 mg/L by SiO₂ content), and the remaining amorphous silica is insoluble. When pH raises above 9, solubility increases, peaking at around 13, but speciation and polymerisation increase as well, and silicate oligomers or polymers can form if the concentration raises above the monomeric solubility. Since pH strongly influence the polymerisation-depolymerisation equilibrium, the only way to dissolve a solution of concentrated oligomeric H₄SiO₄ is first to raise the pH of the solution above 13, then raise silica solubility even more through heat. As last steps, dilution and neutralization (acidification) of the solution are required, to obtain a concentration of SiO₂ below 124 mg/L, and a pH that is back at drinking levels.^10-12

Prior to applying pH corrections, please measure carefully the value you already obtained, as the actual effect of remineralization on pH in real-life applications depends on many factors – e.g., the degree of purity of the water you are trying to remineralize – and it is hard to predict. Then proceed by very small increments.

Notes

Those of you that are already familiar with the method for adding the salts to the water tank proposed by Tea Secrets / Empirical Tea («Wait around 5 minutes or until you think it has dissolved, then move on to the next mineral»²², «To avoid precipitation of minerals, wait several minutes after adding each mineral, shaking occasionally.»²³), will notice that the first of my proposed approaches slightly differs in this. Topics such as mineral dissolution/precipitation kinetics, speciation, and mineral-water interactions (e.g. redox reactions), are extremely complex. From what I understand, there is virtually no model that does full justice to the complexity of reality. For example, an equilibrium model predicts the state of an aqueous system after a theoretical infinitely long time. But actually, each mineral has its own dissolution/precipitation kinetics. Thus, the outcome depends on the reaction path (i.e. the order and duration of each step), while in equilibrium thermodynamics the outcome is independent of the reaction path. In other words, equilibrium models only simulate some ideal world, which is helpful to understand the system better. For these reasons, since the beginning, I adopted an iterative empirical approach. I tested the method I am proposing – for the storage and dissolution of pre-mixed dry recipes – consistently with the salts that I make use of in my recipes (with the exception of CaSO₄, gypsum, CaCO₃ and MgCO₃). The rationale is that grinding the dry crystallized salts increases their reactive surface area – that we know is a key parameter for dissolution, precipitation and adsorption. As these reactions are notoriously slow when no meaningful acid-base interactions occur, if you do this procedure quickly, according to my trials, un-reversible precipitation should not occur during this short time, and all salts should completely dissolve in under an hour, once in the water tank. As long as the salts were evenly ground and the intermediary solution was stirred – when it was promptly poured into the tank, no sediment ever created over time on the bottom, within the correct amount of water. Even using all proposed salts at twice the concentration. I hope you can consider mine just an alternative approach for your testing. My wish is that my experiments can offer the tea community some effective ways to produce remineralized water reliably and to save some time. Whether you are a chemist or not, please feel free to let me know your thoughts on this and to share your results, especially if you encounter any problem.

REFERENCES

Dissolution and Precipitation – Aqion / Harald Kalka
Mineral Solubility and Saturation Index – Aqion / Harald Kalka
Activity & Ionic Strength – Aqion / Harald Kalka
Solubility table – Wikipedia
SaltWiki – Die Hochschule für angewandte Wissenschaft und Kunst Hildesheim/Holzminden/Göttingen (HAWK)
Mineralogy Database – David Barthelmy
Klimchouk, A. (1996). The dissolution and conversion of gypsum and anhydrite. International Journal of Speleology, 25(3), 2.
Morse, J. W., Arvidson, R. S., & Lüttge, A. (2007). Calcium carbonate formation and dissolution. Chemical reviews, 107(2), 342-381.
Ford, D., & Williams, P. D. (2013). Karst hydrogeology and geomorphology. John Wiley & Sons.
Belton, D. J., Deschaume, O., & Perry, C. C. (2012). An overview of the fundamentals of the chemistry of silica with relevance to biosilicification and technological advances. The FEBS journal, 279(10), 1710-1720.
Crundwell, F. K. (2017). On the mechanism of the dissolution of quartz and silica in aqueous solutions. ACS omega, 2(3), 1116-1127.
Lunevich, L. (2019). Aqueous silica and silica polymerisation. Desalination-Challenges and Opportunities, 6, 1-19.
Crouse, D. N. (2016). Prevent Alzheimer’s, Autism and Stroke. CreateSpace Independent Publishing Platform.
in an open CO₂ system with pCO₂=3.408, at 20°C, for a solution containing only pure water and the salt (calculated with Aqion)
Vuong, Q. V., Golding, J. B., Stathopoulos, C. E., & Roach, P. D. (2013). Effects of aqueous brewing solution pH on the extraction of the major green tea constituents. Food research international, 53(2), 713-719.
Zeng, L., Ma, M., Li, C., & Luo, L. (2017). Stability of tea polyphenols solution with different pH at different temperatures. International journal of food properties, 20(1), 1-18.
Zhang, H., Jiang, Y., Lv, Y., Pan, J., Duan, Y., Huang, Y., Zhu, Y., Zhang, S. & Geng, K. (2017). Effect of water quality on the main components in Fuding white tea infusions. Journal of food science and technology, 54(5), 1206-1211.
Vuong, Q. V., Golding, J. B., Stathopoulos, C. E., Nguyen, M. H., & Roach, P. D. (2011). Optimizing conditions for the extraction of catechins from green tea using hot water. Journal of separation science, 34(21), 3099-3106.
Dissolved Inorganic Carbon as Sum of Carbonate Species – Aqion / Harald Kalka
Carbonate Species vs. pH (Closed System) – Aqion / Harald Kalka
Carbonate Species vs. pH (Open System) – Aqion / Harald Kalka
Water Guide – Tea Secrets
Truth Serum recipe – Empirical Tea

How to mix the dry salts of a recipe for long-term storage (easier method, not suitable for recipes containing CaSO₄, gypsum, CaCO₃, MgCO₃, or sodium silicate):

How to produce remineralized water using the previously stored-dry, pre-mixed salts:

How to create a concentrated solution of a recipe, for long-term storage (not suitable for recipes containing CaCO₃, MgCO₃, or sodium silicate):

Recommended method. How to use single-salt solutions to make concentrates for long-term storage, or to directly produce remineralized water:

RECOMMENDED TOOLS (examples only, for Germany)

SALTS & COMPOUNDS ¹⁻¹¹

EXAMPLES OF COMMERCIAL SALTS, BY COUNTRY

Germany

Italy

United States

The Sant’Anna™ Revisited recipes

About the pH of the recipes

Notes

REFERENCES

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SALTS & COMPOUNDS ^¹⁻¹¹