can bacteria form in blowoff bucket and go up tube?

I was just curious - do you have to worry about stuff landing in your blow off bucket, going down through the water, then up through the tube into your fermenter?

I started off with sanitized water in the bucket, but surely over time it will become unsanitized...

Thanks

It is possible, but so is alien abduction. Assuming your blowoff container was filled partially with water/sanitizer mix, all should be well. I can't speak for Iodophor, but with Star San, you're probably safe for the first day or two. After that, it's probably a good idea to change the water out.

That being said, I have a recent batch that sat for 6 weeks with a blowoff in what I know was no longer viable Star San water. Star San generally lasts about 12-24 hours tops in my tap water, but this beer turned out great.

Long story short, try to avoid doing that in the future, but 99% sure your beer will be just fine.