I'm new to brewing beer and want to keep a close eye on SG, but I'm mindful of the potential cost when taking several hydrometer readings. Assuming all my equipment is sterilised, is it OK to return the sample back to the fermenter, or should I err on the side of caution and discard it each time?

For sake of completeness: my sterilisation process consists of soaking the cleaned equipment (hydrometer, wine thief, sample tube, etc) in warm water with a dash of Milton liquid and then rinsing with clean water. When I make cider I'm less worried about wastage since my quantities are bigger and at any rate I get to drink the sample when I'm done measuring, but my beer's less tasty at this early stage and I'd prefer to let every drop mature fully.

Finally, I'm aware this question was asked in a roundabout way 9 years ago but it didn't attract a significant amount of traffic, potentially due to the choice of Title.

Thanks in advance for any insights you can give me!

3 Answers 3


I typically return my sample after taking a reading. If your sanitation is appropriate then you wont have any issues. However, you mention that you rinse with water after sanitizing. I dont believe that's ideal, you are potentially reintroducing bacteria. Once soaked with the sanitising solution, you just leave it dry. That being said I use starsan rather than milton so perhaps there is an important difference.

  • It's a valid point and the question of whether or not to rinse has rattled around my head for a while, with arguments against being that air-drying also has a chance to introduce contaminants, as does handling etc. In my naivety I decided that rinsing with clean water (and shaking most of it off) is better than leaving traces of something that could kill the yeast, and besides, I added over 20 litres of the same water less than a day ago. I will however look into using Star San going forward - seems to be the popular choice around here and I'm not exactly experienced myself ... Commented Oct 27, 2020 at 18:15
  • Star san is an excellent product, well worth getting hold of some.
    – Mr_road
    Commented Oct 30, 2020 at 9:43

I think if you're taking so many hydrometer samples that it's having a noticeable impact on the mass of your final product- you're messing with your beer too much.

I know as a new brewer it's really tempting to keep popping open the lid and checking things, but it typically isn't necessary, and can be harmful. You're more likely to introduce infection- or perhaps just as bad- oxidize your beer badly when thiefing or pouring the sample back.

However- every brewer has their own preferred methods. And if you do properly sanitize all of your equipment- then it should be fine to thief and reintroduce your sample.


I would always discard the sample and I would advise you that you should discard the sample.

You have taken it out of the sanitized low oxygen, low pH environment, put things in it, breathed on it. It is not worth the risk for a pint/half litre of beer. Just bin it. you may take 3/4 readings loosing 2 pints at most over a brew. Why risk the rest of the batch.

You can have sanitised, even sterilised your equipment, but bacteria and natural yeasts floating in the air can land in the sample and the comtaminate your batch, again why take the risk.

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