Basics and units
Water to add to correct the mash
63 °C instead of 66? Two litres of near-boiling water and it is sorted. The tool gives the exact volume to pour in.
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 correct the mash with water?
A mash step missed by three degrees can be rescued. Heating the tun directly works, but easily scorches the bottom and creates hot spots where enzymes are destroyed. Adding very hot water while stirring raises the whole mash at once, with no risk.
The calculation avoids the other mistake: pouring by eye, overshooting the target, then having to cool down. The other way round, a little cold water brings an overheated mash back before the enzymes suffer.
Every addition thins the mash: beyond a few litres, take it into account in the sparge water volume.
How is the volume of water to add calculated?
It is a blend of two volumes at two temperatures:
V water = V mash × (T target − T mash) / (T water − T target)The hotter the added water, the less you need: to raise 20 L from 63 to 66 °C, you need 2.07 L of water at 95 °C, or 1.76 L of boiling water.
The mash volume counts the water and the grain: the mash volume calculation gives it.
Worked example
Values entered
- Mash volume in litres: 20
- Current mash temperature in °C: 63
- Target temperature in °C: 66
- Temperature of the added water in °C: 95
Result from the tool
- Water to add, in litres
- 2.07 L
What the tool does not do
- The blend is assumed to be perfect: stir while adding and wait two minutes before measuring again.
- The tool reports an error if the added water is at the target temperature, or if the calculation would give a negative volume.
- The heat lost by the tun during the operation is not counted.
Frequently asked questions
How can I warm up a mash without scorching it?
Add very hot water while stirring rather than heating the bottom of the tun. If you must heat, do it gently and stir constantly. For a large temperature gap, decoction is another solution.
Can I add cold water to lower the temperature?
Yes. Enter the temperature of the cold water: the tool calculates the volume in the same way. Act quickly: above 70 °C, the enzymes that produce fermentable sugars are destroyed within minutes.
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.
My mash is at 63 °C instead of 66, I have 20 L in the tun and water at 95 °C.
Add 2.1 L of water at 95 °C while stirring, then measure again in two minutes. I'm noting the addition in the brew: you will need to take those 2 L off the sparge water.