Basics and units
Mixing hot and cold water
For sparge water at 75 °C, no need to watch a thermometer: mix boiling water and tap water in the right proportions.
Result
Fill in the values and run the calculation, or try the example.
This is the calculation Krausi uses. Create an account to save it in a recipe or a brew.
Create my accountWhy mix instead of heating?
Heating 20 L of water to a precise temperature takes attention: you overshoot, wait for it to drop, start again. Boiling part of the water and then cutting it with cold water is quicker and lands right on target.
It is the simplest way to prepare sparge water during the mash, or mash water when all you have is a kettle and a tap. It also helps cool water that is too hot quickly.
How are the two volumes calculated?
The calculation is a mixing rule:
V hot = V total × (T final − T cold) / (T hot − T cold)
V cold = V total − V hotBy default the hot water is at 100 °C and the cold water at 20 °C. Measure the temperature of your tap water: in winter it drops to 8 or 10 °C, and the proportion changes.
Worked example
Values entered
- Total volume wanted in litres: 20
- Wanted temperature of the mix in °C: 75
Result from the tool
- Hot water in litres
- 13.75 L
- Cold water in litres
- 6.25 L
What the tool does not do
- The cold temperature must be below the target temperature, itself below or equal to the hot temperature.
- Heat losses from the vessel are not counted: a cold bucket costs you one or two degrees.
- At altitude, water boils below 100 °C: enter the actual temperature.
Frequently asked questions
At what temperature should I sparge the grain?
Between 75 and 78 °C. Hotter, the water extracts astringent tannins; colder, the sparge carries away fewer sugars.
How do I get 50 L at 65 °C?
Mix 28.1 L of boiling water and 21.9 L of water at 20 °C.
And with the assistant?
Ask Krausi the same question in plain language: he picks this tool, does the calculation and files the result in your project.
I need 20 L of sparge water at 75 °C, I have boiling water and the tap at 20 °C.
Mix 13.75 L of boiling water and 6.25 L of tap water: you will have 20 L at 75 °C.