# Calculating Mash Water Volume When Brewing with Pumpkin

Okay, so pumpkins are not in season and I'm substituting winter squash (acorn/butternut) for my pumpkin ale recipe, but the concept remains the same as if it were pumpkin. I've never brewed with pumpkin (or any other fruits/vegetables for that matter), so I have some questions.

The grain bill is 13.75 lbs. If I weren't using pumpkin I would use 1.25 quarts of mash water per pound of grain, equaling 4.3 gallons.

My questions is, if I'm adding about 8 pounds of pumpkin, do I need to increase my mash volume to account for that, and if so, by how much?

Since the pumpkin will be saturated with water, I know I don't need to account for absorption in the same way that I do with the grains, but is the water displaced by the pumpkin enough to keep the grains fully submerged? Do I need more sparge water?

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I think you meant to say 1.25 quarts of water per pound – Dean Brundage Apr 2 '10 at 15:05
Thanks Dean! Just fixed it. – markskar Apr 2 '10 at 15:14
FYI Google tells me that (boiled) pumpkin is about 6% carbohydrates (1% protein, and not much else other than water) Barley is about 73%. Make what you will with that. Edit: My maths says that your normal mash is about 20% carbs) – DarcyThomas Nov 21 '13 at 1:53

I brew a sweet potato beer and I assume 1qt/lb of sweet potato. I also adjust the thickness by eye after that. The water to grist/veg ratio isn't really all that critical. Nor is it all that different if you have to adjust the water a little up pr down by 10-15%.

The key is to have enough water in there that it doesn't become a gooped up mess. The mash needs to be liquid enough to lauter. This is where mash experience just comes into play. Its more of a feel issue than a set #.

Good luck.

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Thank you! I was starting to wonder if I would get an answer in time for tomorrow. I've never done anything like this so I appreciate hearing from someone who has. I was reading that sweet potatoes can make really interesting beer. I'll have to try that sometime. Cheers! – markskar Apr 2 '10 at 20:10
I wrap 4 sweet potatoes in foil, bake for 4 hours at 400F. They get really sticky and caramelize a bit. Seperate flesh from skin and in the mash they go. I usually bake the night before. – brewchez Apr 5 '10 at 12:32

Google tells me that (boiled) pumpkin is about 6% carbohydrates (1% protein, and not much else other than water) Barley is about 73% carbohydrates.

So my back of the envelope maths says that your normal mash is about 20% carbs)

The back of the envelope goes on to say:

If you put in one quart of mashed boiled pumpkin, put in one quart less water and 1/4 pounds less grain. Assuming that does not make the beer mash too gluggy.