Water Volumes for Brewing All Grain

  • It is important to use the right amount of water because…
    • Too much water = too much wort at a lower gravity
    • Not enough water = too little wort at a higher gravity

How Much Water Do I Use for All Grain Mash Tun brewing?? 

  • Calculate backwards from your batch size
  • Batch size: 5 gallons
  • Kettle Loss: Post Boil / Post Cool Down losses at the bottom of your kettle; proteins, hops, misc. sludge
    • Can be as much as 3 quarts depending on hopping rates
    • Brewstock’s system is ~2 quarts of loss, +- depending
  • Boil Rate: How much is boiled off:  ___ gal/hour … GPH if you will. 
    • Typically 3-4 quarts per hour
    • Depends on your system! Propane burner? Electric Kettle? Stove top? 
  • Boil Size = Batch size + Boil Rate + Trub Loss
    • Example: 5 gallons + 3 quarts + 2 quarts = 6.25 gallons boil size
  • Grain Absorption: How much liquid is lost in the grains
    • Typically ~0.5 quarts per pound of grain
    • 12 lbs of grain x 0.5 quarts = 6 quarts of loss (1.5 gallons) in the mash tun
  • Total Water: How much water do I need to brew 5 gallons of beer
    • Batch Size + Kettle Loss + Boil Rate + Grain Absorption = Total Water
    • 5 gal batch Size + 0.50 gal kettle loss + 0.75 gal boil off + 1.5 gal grain absorption = 7.75 gallons

Calculating it forwards…

  • Start with 7.75 (or 8) gallons of water
  • Mash in 12 pounds of grain, after the mash, the grains will absorb about 6 quarts (1.5 gallons) of liquid.
    • 7.75 gal – 1.5 gal = 6.25 gal
  • Fire up your 6.25 gallons of wort to a boil, the boil should drive off about 3 quarts (0.75 gallons) of liquid.
    • 6.25 gal – 0.75 gal = 5.5 gal
  • Cool your 5.5 gallons of wort, the cooling process should drop out about 2 quarts (0.5 gallons) of trub junk.
    • 5.5 gal – 0.5 gal = 5 gal
  • Put 5 gallons of wort into your fermenter. 
  • How do I know what the variables are on my system?
    • Trial and Error! 
    • These numbers can change based on hopping rates, types of grains used, environment, humidity, etc.
    • A quick and easy way to figure our your average boil rate for your rig… Fill your kettle with a specified amount of water.. Try 6 gallons (a nice even number) to mimic a brew day, and boil for 60 minutes. After the boil, let it naturally cool down and measure the amount left over. The delta is your boil rate per hour.

Quick note for Brew in a Bag brewers… This process is nearly identical with the exception of grain absorption. 

  • If you squeeze the bag (encouraged), there will be significantly less grain absorption loss
    • Try targeting somewhere around 0.2 – 0.3 quarts per pound lost in the grains
    • Subsequently, you might need ~0.75 gallons less starting water.