Just bottled my first contaminated beer, got lazy and didn't freeze/boil the watermelon I added to a wheat beer and got lacto(?) contamination and an amazing sour watermelon beer as a result!

But, now I want to know if it's time to chuck the fermenter that had the contamination out (or put biohazard stickers on it and keep it for a deliberately sour beer). I ferment in plastic pails, so no great cost to replace and probably hard to really clean.

Reading around, there are quite different opinions on whether there is enough starsan or bleach in the world to restore a pail that's carried a contaminated batch; so I thought I'd ask the experts.

  • 3
    I don't know if you can clean it. As you say, there are conflicting opinions on this. I trust The Mad Fermentationist (google for his blog), and he says that Brett & Co. are easily destroyed with a long soak in sanitizer. Others say they practically can't be destroyed. HOWEVER, if the beer came out tasty, then I would NOT destroy the bugs. Instead, just flag that bucket as "FOR SOURS ONLY" and use it whenever you make sour beers again. You might just grow up a nice house strain of bugs that keeps you pleased for years.
    – GHP
    Apr 11, 2011 at 13:54
  • 2
    Please answer as an answer, not as a comment. Answering a question with a comment can't be upvoted or marked as best answer.
    – Hopwise
    Apr 11, 2011 at 18:42

4 Answers 4


Have used plastic, glass, and stainless fermentors with bacteria and yeast without them contaminating the next batch. Just need to make sure you do a good clean and proper sanitization.

As always, there are many caveats:

  • Are the fermenters cleanable and sanitizable? Do they have scratches or hiding places (see valves)
  • Can you really clean and sanitize the tubes?
  • Are your being very paranoid about sanitization?

But, if you are careful, you should not have any problems.

PS forget where I have heard this but bacteria is like yeast. We all seem to do fine switching yeast strains between brews, we should be able to do fine using (or not using) different bacteria between brews. That is the logic I use :)


Clean it with warm sanitizer. Fill it with normal strength sanitizer and leave it over night. It will be good to go IMO. Clean and sanitize the lid also really well.


What's the condition of the contaminated pail? If it's a really old pail, there might be hard to clean scratches and cracks that can harbor the infection into your next batch. That said, I think if you are careful with washing it out multiple times and following the standard sanitization routine, it's probably safe to keep the bucket.


Based on much experience where I had many batches go sour unintentionally after the first one did, I can honestly recommend that any and all plastics and rubbers be replaced or dedicated to sours after it happens just one time, just to be on the safe side. I even tried to decontaminate with a soak in strong bleach solution for several weeks, but this effort was NOT successful for my old plastic buckets, with or without scratches. In my experience, odds were close to 50/50 of preventing contamination on future batches. It is for this reason that I have converted to all glass or stainless fermenters for all batches ever since that time, and have never had a problem after. Your mileage may vary, but I know I don't find it worth the risk to try to reuse these materials after they've seen wild beasts at least one time, regardless of visible or non-visible scratch marks or anything else.

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