Mash Out Water

Sorry to beat a dead horse, but I couldn’t find an definitive answer searching the forums.

My wife and I have always fly sparged, and have always skipped the mash out. We have never had a stuck sparge and all of our beers have turned out pretty tasty. On our last brew day, though, we talked about doing a mash out just for comparison. So, we’re planning on brewing two identical recipes next time—one using mash out and one not.

We’re confused about the water calculations. Is the amount of mash out water subtracted from the sparge water? Or, is it subtracted from the mash water? Or, do we use the amount of mash water as calculated, mash out with as much water as necessary to get to 168F, and then sparge until we have our pre-boil volume?

The last question might have answered our question, but it never hurts to ask.

Also, we’re assuming mashing out equal to or slightly less than 170F is better than going well over.


The idea is to raise the main mash from its saccarification temperature to the high 160’s. I do that without an infusion since I run a RIMS. But to do it via infusion, you would add an amount of boiling water to raise the entire mash to that mash out temp. That infusion is generally considered to be a portion of the sparging water. The only difference is that sparging water is around 168F and the mash out water is boiling. I know that Promash and Beersmith can calculate the volume of boiling water needed for the mash out infusion. I’m sure there are other calculators out there too.

For the last question, its best to be generally around that 168F temp. Going well above that can invite a bit more risk of extracting undesirable components from the grain. Of course, using low alkalinity sparging water and making sure the mash pH is in the appropriate range is very important for avoiding that undesirable component extraction.

All you do for a mash out is heat your mash and let it sit at 170F for 10 mins and heat your sparge to 170F as well. No need for extra water or recalculations on the water. Heat-rest-sparge. That’s it.

That’s good stuff. Thanks! :cheers:

Not so easy to do in a plastic cooler! Piece of cake in a metal pot.

I brewed an American wheat yesterday and did a fly sparge for the first time instead of batch sparging as I normally do. I mashed at 152 for 80 minutes. In the past I raised my mash temperature to 170 for the mash out. I tried something different, I heated my sparge water to 190 degrees and started to fly sparge. The temperature of the mash raised to 170. I only calculated the amount of water in quarts per pound of grain for the mash. During the sparge I collected wort until I hit my pre boil amount which is 8.25 gallons. (I lose almost three gallons during the boil because of the size of the kettle)It just so happened I ran out of water in the HLT when I hit my pre boil mark.