Knowing how to harvest, wash, and save yeast is a valuable skill for any brewer to have. This is one of the best ways to save money while homebrewing and is also a process that will allow you to save and reuse wild or unique strains of yeast. During this tutorial, we’re harvesting wild yeast from the bottom of a fermenter that was used for one of our “log beers”. Good wild yeast experiments like these would make any homebrewer want to save yeast so it can be preserved and used forever. Read this article next to learn how to make a yeast starter with washed yeast. You'll need to know how to make a yeast starter with your harvested and washed yeast in order to ferment another beer with it.

Video Tutorial

Here is a full video tutorial that illustrates the steps below

Items Needed

• Leftover yeast from a previous batch of beer
• 5 Gallon (18.9 liter) Carboy
• 3 Gallon (11.4 liter) Carboy
• Distilled Water
• Funnel
• Mason Jars
• Star San or a similar food-grade sanitizer

Follow These Steps

1. Start with the leftover yeast and dregs at the bottom of a fermenter - pour any leftover beer out

We cold crashed this beer so there's a pretty thick layer of yeast at the bottom of the fermenter

2. Pour distilled water into the bottom of your fermentation vessel in order to break up the yeast cake at the bottom

3. Shake it up - you want to get all the yeast that was lying at the bottom of your fermenter into suspension

Now our yeast cake has become fully incorporated with the distilled water

4. Transfer your water/yeast solution into a clear carboy using a funnel - make sure the funnel and carboy have been sanitized

If there's leftover yeast in the fermenter after this, feel free to repeat steps 2-4

5. Turn the carboy onto its side and let your yeast/water solution settle for 30 minutes - you can add a sanitized lid to the carboy if you're worried about contamination

Before

After

6. After 30 minutes, the water/yeast solution should have separated into a milky layer on top and a sediment layer on the bottom

You should see a good bit of separation after 30 minutes

7. Pour the milky layer on top into your smaller 3-gallon (11.4 liter) carboy - turn the 3-gallon (11.4 liter) carboy onto its side and let it settle for 15 minutes

You won't see as much settling this time around

8. After 15 minutes, pour the top layer into sanitized mason jars 

Don't screw the lids on too tight, just make it snug

9. Put your mason jars filled with yeast water into a fridge for one final stage of settling

10. Settling times will vary, but we checked on our jars two days later to find a nice layer of yeast on the bottom

Make sure to read this article to learn how to make a yeast starter with the yeast that you've successfully washed, harvested, and saved.