I'm wondering what the easiest way to wash yeast after a brew might be, with the aim to store it in the fridge. The usual recommended method I've seen is to boil the water used for washing with the containers together first - but it seems to me quite a slow process (have to wait for cooling).

Would it be possible to just wash the yeast with tap water - or alternatively wash the yeast with starsan?

If it helps the area I'm in has pretty good water quality - spring water with minimal treatment and no heavy mineral content.

2 Answers 2


Washing yeast with Starsan will kill most of the yeast. Just like it kills off other microbes in your equipment when you sanitize.

All stored yeast should really be used within a few weeks. I prefer to just leave the beer on top of the yeast in a mason jar. Washing is not necessary. I decant the spent beer when I am ready to pitch into a new starter wort the day of brewing or the night before.

Some people do use straight tap water to wash with but there is a risk if picking up microbial contamination. Also boiling the water helps to de-oxygenate it to a point which is something else you want when storing yeast. (Another reason why I just like the spent beer on top)

  • I've collect yeast from blow off bottles filled with starsan with great results. Most yeast is tolerant to ph levels below starsan. While it may kill off some yeast, it may be a good thing to thin the heard of weak walled cells. Jul 13, 2016 at 13:51
  • @EvilZymurgist Interesting. I might have to try a microscopy experiment to see what's really going on there.
    – brewchez
    Jul 13, 2016 at 18:04
  • If you think about it, yeast blowing off into sanitizer is likely to overwhelm and neutralize the sanitizing power pretty quickly, leaving later portions of yeast to survive unaffected. Also, the sanitizing power of StarSan is more than just a drop in pH, it contains a surfactant and isopropyl alcohol as well. These aren't likely to have a huge effect at low concentrations and I'm sure the yeast you collected was perfectly fine, but I still wouldn't recommend this as a standard practice. Jul 16, 2016 at 1:57

If tap water is safe to use or not will depend on who you ask and where in the world they live. I'd seek advice about that locally.

Around where I live pretty much everyone I know just use straight tap water for re-hydration, topping up and washing yeast. Few people have any qualms about it. But that's somewhere where everyone has grown up with clean and safe tap water.

Get an answer from somewhere where water hasn't always been safe, even if it is now, and the answer would be very different.

  • Seems you are onto something there - I asked at a local homebrew shop and they said washing with tap water should be fine where I am. They mentioned something similar about it depending on the region - levels of cloronation, mineral content etc can vary.
    – Tim
    Aug 3, 2016 at 0:51

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