When it comes to adjusting water profiles for beer brewing, it can get complicated. While there are plenty of online calculators that can help you add minerals to your tap or distilled water, what if you want to lower the concentration of something like Iron or Magnesium without building an entire new water profile from RO water? That is where Dilution can be a great tool.

What is Dilution?

Dilution means blending your water with distilled or RO water—a ‘blank’ profile that contains minimal minerals. This reduces the concentration of all minerals by the same ratio. For instance, a 1:1 dilution is half of each mineral level in your profile. You can also calculate more specific dilutions to reach your target mineral concentrations. However, keep in mind that dilution affects all parameters evenly, not just a single mineral.
If you are not wanting to just half everything in your profile, you can do the calculations to figure out exactly how much to dilute your water to make the perfect brewing profile.
One negative with dilution is that it will dilute everything, not simply the parameter you are targeting.

Calculating the Dilution for your water profile

1:1 Dilution Example: Let’s start with a simple example and then we’ll break down the formula.
Let’s start with a basic example. Suppose you’re aiming for 50 ppm calcium in your water, but your starting water contains 100 ppm. A 1:1 dilution with distilled water (half tap water, half RO) will reduce calcium to 50 ppm. If you’re using 2 liters of water, you would blend 1 liter of tap water with 1 liter of distilled water to achieve this

Dilution Formula:

The equation you will use to calculate dilution is the following:

Volume of Tap Water= Desired Total Volume x (Desired Parameter Concentration/ Current Water Concentration)

Let’s go through a few examples.

For a dark beer, if you want 125 ppm calcium from a starting concentration of 200 ppm and need 3 liters of water, the formula becomes:

Volume of Tap Water= 3L x (125 ppm Calcium/ 200 ppm Calcium)
Volume of Tap Water = 3L x (0.625)
Volume of Tap Water= 1.875 L

Then you can do the calculation of 3L- 1.125L mean you’ll need 1.125L of RO/Distilled Water to go with your 1.875L of Tap Water. This combination will result in 125ppm of Calcium.

Another Dilution Example:

For an IPA with a target of 30 ppm magnesium, starting from 85 ppm magnesium in your water, and needing 5 gallons of water:

Volume of Tap Water= 5 Gallon x (30 ppm of Mg/ 85 ppm of Mg)
Volume of Tap Water= 5 Gallon x (0.35)
Volume of Tap Water= 1.75 Gallon
5 Gallon- 1.75 Gallon = 3.25 Gallons of RO/Distilled Water

Important Notes on Dilution:

⦁ Verify RO/Distilled Water Purity: Ensure your RO or distilled water is as close to zero ppm as possible for accurate dilution results. Use a test strip to confirm minimal mineral levels before blending.

⦁ Non-Selective Dilution: Dilution affects all parameters, not just one. If targeting a specific mineral reduction (like iron), note that other minerals will reduce proportionately. Re-test your water profile after dilution to confirm levels, as pH and alkalinity might shift differently.