While calculating the overall water necessary to conduct a  full mash , batch sparge  and boil it is important to note how much water will be lost in the spent grains.  I use the basic equations below when calculating the amount of water necessary when brewing an all grain beer.

Amount of Water for Mash = (Pounds of Grain) x 1.25 quarts/pound (divide by 4 to get gallons)

Amount of Water to Batch Sparge with = (Final Boil Volume) + (Shrinkage/Evaporation) + (Equipment Losses) + (Spent Grains) – (Amount of Water for Mash)

From what I have experienced on my brewing rig spent grains absorb about 20% of there own weight in gallons, here is a chart that can be used for reference.  This estimate is based on my single infusion mash with batch sparge  in a 60 quart cooler with a grain crush around .039.

Total Grain Weight in Pounds x .20 = Approximate Gallons of Water Absorbed by the Grains


Pounds of Grains Gallons of Water Lost
5 1.00
6 1.20
7 1.40
8 1.60
9 1.80
10 2.00
11 2.20
12 2.40
13 2.60
14 2.80
15 3.00
16 3.20
17 3.40
18 3.60
19 3.80
20 4.00
21 4.20
22 4.40
23 4.60
24 4.80
25 5.00
mashing in a cooler

mashing in a cooler

All-grain brewing is essentially brewing a beer from scratch and not using any malt extract.  It describes the process by which the sugars from the grains are extracted and become the beer.  The two steps that make up all grain brewing are mashing and lautering.  Mashing was described in the article All Grain Brewing — Mashing , this is a follow up to it and will be describing how to get the wort out of the mash. 

What is Lautering?

The term lautering is used to describe the process by which the mash is separated into wort and grains.  This process has three basic steps mash out, draining off the wort and sparging.   The end results of lautering is a brew kettle filled with wort to the desired pre-boil volume.

The whole process goes something like this:

  • Malt is crushed and added to mash tun (mashing)
  • Malt is soaked with 160-165 water at a water-to-grain ratio of 1.25-1.5 quarts per pound to achieve a mash temperature of 150-155 degrees. (mashing)
  • Mash is usually held at that temperature for an hour, then drained into the brew pot. (mashing)
  • Additional water at around 160-165 F is then added to the mash. (lautering)
  • Mash is stirred and settles for about 30 minutes then drained off again to the brew pot. (lautering)

Equipment Needed for Lautering

Sparge water pot–  A large pot that will be used to heat up your sparge water.  If you are planning on brewing 5 gallons of beer you are going to want about a 5 gallon pot to use as your sparge water pot. 

Wort boiling pot–  A large pot that will be used as the brew pot, keep in mind it needs to be at least a 8 gallon pot for a 5 gallon brew recipe.  The mashing/lautering process will extract about 6-7 gallons of wort which will be used during the boil.  Purchasing a turkey fryer(7 gallon pot with burner) for this is highly recommended and works well.

Steps to Lautering

1. Mash Out
2. Draining the Wort
3. Sparging

Mash Out

This step is usually only necessary for thick mashes, less than a grist-to-water ratio of 1.25. The process of mashing out involves raising the mash temperature to 170 degrees for a few minutes before draining off the wort.  If using a cooler mash tun, this can be done by adding small amounts of boiling water to the mash.

Draining the Wort

Finally after an hour has pasted the time has come to drain off the wort into the boil pot.  Open or take off the top of the mash tun.  You first need to recirculate 2 quarts of wort.  To do this open the valve slowly and collect the wort into a bowl/pot, then gently pour it back into the grain bed.  Repeat the recirculating until the wort appears clear and free of any debris.

draining off first 2 quarts

draining off first 2 quarts

Next drain the wort carefully into the boil pot.  I usually drain through a hop bag just to collect any grain husks that may of made it through.  Watch out not to turn the valve too quickly, it may suck fine particles into your filter(SS braiding or false bottom) and clog the flow.  Fill the pot slowly; make sure the wort is not splashing into it.  Splashing at this point can cause long term oxidation damage to the flavor of the beer.  After all of the wort has passed through it is time to add the sparge water and begin sparging.

draining initial wort into boil kettle

draining initial wort into boil kettle


The most common type of sparging for home brewers is batch sparging. Batch sparging involves large volumes of water being added to the grain bed at once rather than continously. Sometimes two or even three sparges are necessary to collect all of the wort.

To begin this process use the equation below to calculate how much sparge water is neeeded for your recipe.  Heat up the water to 165-175 degrees based on your recipe.  You can start this before your mash is ready.  The water will be added to the grains after the initial wort is drained off. 

Amount of Water to Batch Sparge with = (Final Boil Volume) + (Shrinkage/Evaporation) + (Equipment Losses) + (Spent Grains) – (Amount of Water for Mash)

Final Boil Volume = 5.5 Gallons (accounts for trub loss)
Shrinkage/Evaporation (~.5 gallons)
Equipment Losses (~1 gallon)
Water Lost in Spent Grains (link describes how to calculate)
Amount of Water for Mash (1.25-1.5 x pounds of grains used)

adding filtered sparge water to heat

adding filtered sparge water to heat

Once you have drained the initial wort off you need to close the valve to the mash tun. Next slowly pour in your sparge water. Let the new mash sit for 15 minutes, then recirculate it and drain it off into your brew pot. Repeat as necessary until you achieve the desired pre-boil wort volume.  Bring your kettle to a boil and finish out brewing the rest of the beer.

Thats it for lautering, if you want any more information check out our All Grain section for more articles regarding all grain brewing.  Feel free to post questions/comments below.