Yeast Washing: Reusing your Yeast

by Brad Smith on July 25, 2008 · 32 comments

Washing yeast to reuse it in another batch of beer is a great technique to have in your home brewing arsenal. Yeast washing is a simple process used to separate the live yeast from the underlying trub (hops and spent grains) left at the bottom of your fermenter when making beer.

With the high price of hops and malt, yeast washing is a great way to save a few dollars and also build a strong yeast culture as a basis for a yeast starter. Rather than purchase new yeast each time you can wash and reuse your yeast across as many as 5-6 batches spread out over a period of months by reusing yeast from your primary fermentation.

Yeast washing is remarkably easy to do, involves minimum equipment and can be done in a short period of time. All that is required is two sanitized mason jars, some distilled or pre-boiled sanitized water and some plastic or foil to put over the jars. Sanitizing or sterilizing everything involved is critically important as yeast is susceptible to infection.

Washing your Yeast

Start by sterilizing your two jars by boiling them in water or immersing them in a high quality sanitizing solution. Prepare a few quarts of sterile water by pre-boiling it and then cooling it to room temperature. Use sanitizing solution such as iodophor to sanitize the rim of your fermenter.

If possible, you want to draw your yeast sample from the primary fermenter as it contains more active yeast than the secondary. Harvest the yeast immediately after racking your beer off to the secondary, as you want to minimize the chance of contamination. The primary will contain a layer of thick trub. You need a bit of liquid to work with, so add a quart of sterile water to the primary if needed.

Swish the fermenter around several times to break up the trub and then allow it to settle for a few minutes. Pour the liquid from the top of the trub into one of your mason jars, being careful to keep everything as sterile as possible.

After collecting your yeast and trub put some foil or plastic wrap over the top and seal it with a rubber band. Put the mason jar in your refrigerator for 30-60 minutes which will help it separate. Ideally you will see a clear separation between the liquid and sediment. The liquid contains suspended yeast, while the sediment is primarily trub.

The next step is simply to pour off the liquid suspended yeast from the top of your mason jar leaving as much of the sediment behind as possible. Pour your yeast into a second mason jar, cover it and place it in the fridge again for an hour or so.

If you still have a significant amount of trub at the bottom of the second mason jar, you may want to consider mixing in some sterile water and washing the yeast again. If not, you can store the yeast for several months in the refrigerator until you are ready to brew again. If you plan to store it for an extended period you may want to consider transferring it to a flask or bottle with an airlock and keep it in the refrigerator to prevent contamination.

On the day before you brew, add some wort to your yeast create an appropriately sized yeast starter for your next batch. If you want to use your yeast across several batches you can either split your starter and store part of it for later use or repeat the entire process to collect yeast from the primary again.

If you do collect yeast across several generations, I recommend not exceeding 4-6 generations of reuse as eventually some wild yeasts or bacteria will make there way into your yeast.

Washing your yeast is a great way to save a few dollars while keeping a healthy supply of fresh yeast available for your favorite brew. Thanks again for visiting the BeerSmith Blog. As always, your subscriptions, comments and social bookmarks are appreciated.

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{ 28 comments… read them below or add one }

William Johnson August 3, 2008 at 1:06 pm

toward the end of the article on yeast washing, it states: “On the day before you brew, add some wort to your yeast create an appropriately sized yeast starter for your next batch.” How do you add wort to the washed yeast the day before you brew? Totally unclear…please advise?

Brad Smith August 3, 2008 at 1:49 pm

The article on yeast starters linked in as part of the quote you mention in the article tells how to create a yeast starter for your beer. For example, a 5 gallon batch should have a 1-2 liter starter.

Dakota March 2, 2009 at 2:59 pm

I think this is a great idea.

eolaughlin September 29, 2009 at 6:25 am

Would it be better to use yeast from the secondary fermenter since this yeast is more alchol tolerant? There are also less hops debris etc.

admin September 29, 2009 at 5:06 pm

Actually the yeast from the primary fermentation is more active which is why it is generally preferable for reuse.

DJBeerStein October 13, 2009 at 1:49 pm

I have been wanting to recycle my yeast for a while now. I am currently working on a frozen yeast bank, but this yeast washing technique will be great in the meantime.

I am wondering, if I wash the yeast out of the primary of a 5 gallon fermenter, will it be enough yeast to pitch into a 5 gallon batch of cooled wort? I would most likely use a yeast starter, but if you know, please let me know if it’s sufficient either way.



Brad Smith October 14, 2009 at 7:47 pm

I would recommend a starter unless you are going to reuse the yeast immediately. It is best to have active yeast in your beer as opposed to yeast that have been dormant for some time.

Tom March 21, 2010 at 9:13 am


What are your thoughts on washing the yeast as opposed to simply saving some of the slurry (in the fridge) for a future brew (say for a brew taking place 2 months later)?


admin March 21, 2010 at 7:47 pm

Tom – If you are going to save the yeast for an extended period (2 months), I prefer washing as it separates the yeast from the tannins and trub that over time could lead to off flavors.

tom December 9, 2010 at 2:11 pm

can I use the mason jar lids not the foil or plastic .

Brad Smith December 9, 2010 at 6:01 pm

Yes, but you might want some kind of airlock initially as the yeast could still ferment a bit and build up pressure.

John January 17, 2011 at 6:56 pm

I poured the slurry from my primary into a mason jar and put it in the fridge. It’s been there for two days. Is it too late to wash it?


Brad Smith January 17, 2011 at 7:10 pm

It takes a few weeks for slurry to fully degrade, so you should be fine. Just wash the yeast as soon as possible.


concrete cleaning richmond va February 20, 2011 at 11:02 pm

I noticed, and have experienced, the manhandling of the carboy when carefully pouring out the top layer. It might be easier to get the top layer off if you let everything settle out while the carboy is on it’s side. A gentle tilt pours the top layer off easily instead of churning up the layers when tilting from the bottom. Just a thought.

John March 1, 2011 at 10:15 am

So basic could you do this and is it pratical, if you were to empty the primary fermter, so that all you have is the yeast cake then add a 1 liter of sterile water, let it sit ,,,to sepate into a 2 liter flask then repete step again would this work

mick June 20, 2011 at 9:28 am

I have been brewing for years now, since I have found this web site I have learnt so, keep up the great work and I started out as a hobby but not now, thanks guys

Mark August 17, 2011 at 12:14 pm

How does this compare with harvesting yeast from the bottom of bottles? Is that a viable option as well?

p.d November 26, 2011 at 7:36 pm

just salvaged and recycled 1968 ale yeast. airlock activity stopped in my 5 gal primary. i added some primeing sugar and bottled it up. meanwhile in my brew kettle i had my next ipa recipe cooling. so i swished about 1/2 gallon sterile water into the trub of my just emptied carboy and washed it out into 2 containers. i poured the top layer of one into my new wort and overnight it is beautifully krausening. i have saved the other container in the refer. i love it. so far so good.

Ben January 23, 2012 at 5:05 am

Great tip, I have tried this, ok… so I now have three jars, after leaving it for an hour of so there was a yellowy liquid on top which I poured into a sterilised jar, and I repeated the process into another sterilised jar an hour or so later. However now after leaving it over night I have a thick layer of browny stuff floating ontop of the yellowy clear liquid in the first jar, Is this the bit I actually want? is this the yeast? or do I want the yellowy clear liquid?

Thanks in advance.

Brad Smith January 29, 2012 at 2:00 pm

You actually want the clear liquid.

Ben February 10, 2012 at 2:59 am

Hi I have done this, i kept the yeast in the fridge for about 3 weeks, i added the yeast to some starter as described above last night but nothing appears to have happened, no bubble or anything, is this normal or have I not succeeded in saving the yeast this time? Thanks

Dave May 11, 2012 at 2:30 pm

I just found this site andI am grateful for the instructions on washing yeast. This is definitely a technique I will use in the future. I made a batch of Kolsch with White Labs WLP029 Kolsch/German Ale yeast and racked it to secondary about 2 weeks ago. After racking, as an experiment, I poured off the remaining liquid from the primary fermenter bucket. Then I sanitized the original plastic vial that the yeast came in and scooped the residue at the bottom of the fermenter into the vial and put it in the refrigerator. I know this also contains some trub and spent hops in addition to the yeast cake. It’s been in the fridge for about 2 weeks now. Is it too late to wash and reuse this yeast, or should I just use it as-is to make a starter, or am I just better off tossing it and using your method next time? Once again, thanks for the instructions.

Butch September 11, 2012 at 6:41 pm


I was successful with your yeast washing tips and collected 4 half-pint Mason jars of clear washed yeast. Can you use the washed yeast similar to the store bought liquid yeast or use it in a yeast starter? How many half-pints would I need to use for a 5-gallon batch?

I’m new to home brewing and enjoy reading your articles.

Thanks a lot for your help.


Brad Smith September 12, 2012 at 4:17 pm

One would be fine, though you may want to pitch it into another starter if it has been more than a week or two since you collected it.

Kyle November 13, 2012 at 8:43 am

Brad – I’m a true beginner, so forgive the brewing 101 questions… I’ve heard that pitching directly onto the yeast cake is acceptable and that it has a whole lot more yeast than a packet or vial of fresh yeast.

From your 9/12/12 reply it sounds like you don’t need a starter if you’re using the washed yeast within a week or two and that only one 1/2 pint mason jar would be enough for a normal batch of beer. So I’m guessing I’d go through your sterilization procedure, put the sealed jars of washed yeast in the fridge, and a week or so later pitch I could a jar without a starter, correct? Anything beyond a couple weeks and I’ll want a starter.

How about a high gravity beer? If the OG is going to be over, say, 1.060 would I pitch two half-pint jars? Three? Is there any real danger of over-pitching?

Thanks so much – I’m loving your homebrew blog.

Jez January 4, 2013 at 11:36 am

This is a decent article, I have 2 things to add:

1) I have a gallon glass jar that gets sanitized. The chilled sanitized water is put into this. I usually will boil the water on a night before a day off. I get up, move the cooled water to my big 1-gallon sanitized jar, and then transfer my beer out of my fermenter into bottles or a keg, then pour the water in the bucket.

2) Give these “rests” 20 minutes. You can then pour the “top” of the yeast-water back into the 1-gallon container. Again, rest 20 minutes and then pour the “top” of this yeast-water into your jars. I do put lids on them (there shouldn’t be any further fermentation to cause pressure on your jars, although, I do crack the lids in the fridge and re-tighten after 24 hours. You’ll hear a “poosh” if there is any activity. If your beer was fully fermented, this shouldn’t be an issue – you’re adding water that is fermentable-free) and tighten them.

I had a Budvar yeast I just used after 3 months – made a starter like I do with all yeasts (4L in this case, with 400 g of light DME) and got a HUGE cake after 3 days. Put this in a Czech Maibock and it took off like a rocket for the first 24 hours.

Also, if you plan on harvesting a yeast on a dry-hopped beer, I would suggest transferring the beer into another vessel for dry-hopping and THEN wash the yeast from the non-dry-hopped vessel. High hop levels tend to kill the viability of yeast.

Sven Enterlein April 24, 2013 at 4:28 pm

I have been looking around a while but still haven’t found a decent explanation as to why I have to separate and remove the trub before freezing the yeast.

So here’s my story:
I made a primary culture by adding the content of a (preincubated) Wyeast Activator pack (1056) to 1.5 L of wort (made with 1 cup DME per liter of water and some 0.2 oz or so Magnum hops). I stirred it overnight and the next day used ~100 mL to inoculate another 1.5 L starter to be used in my BVIP. I placed the primary culture back on the stirrer and let it go for another 24 h. I then put it into the fridge for about 20 h so everything could settle. I poured off the supernatant and added ~400 mL of a wort (again 1 cup per liter) containing 10% v/v glycerol. To resuspend the yeast I stirred for a good 10 min and froze ~45 mL portions.

I know that the cultures will contain some trub and even hops “flakes” but since they do not amplify when used in a new starter culture I don’t quite understand why I should go through the extra step of washing the yeast before freezing. Since I work with mammalian cells for a living I am used to putting as much protein into the freezing medium as possible and in my opinion the additional proteins from the trub should actually aid in the preservation during frozen storage. Am I missing anything? I am very eager to learn since I think having happy yeast cultures in the freezer will help reduce the expenses for frequent brewing :)

Jon Rausch September 30, 2013 at 3:24 pm

So I have a new conical fermentor, I have read to harvest at the end of active fermentation by opening the bottom valve and waiting to the trub/slurry becomes white. Is this correct? Do I still need to wash the yeast? Do I wash it by just adding it to sterilized water and performing the above steps? Do I harvest before dry hopping?

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