While waiting for the Foundry to get back in stock, I found a scratch-n-dent sale on a 5 gallon pot on amazon and decided to give an extract a try while waiting. Extract brewing seems to have it's own specific pitfalls and a couple tips have stuck in my mind from various places that aren't mentioned in the brew instructions.

  • Sanitize the top-off water going into fermenter
  • Add LME at end of boil (-15 mins)

Any reason not to add the LME at the "end" of the boil? Seems to be to help prevent scorching. Also, how do you go about santizing the top-off water? Only reasonable thing I can think of is to boil it the night before and let it sit.

3 Answers 3


You ALWAYS want to sanitize your top off water if you are getting it from tap. Bottled water is not necessary but recommended. Additionally, you need to get rid of the chloramines as they will give you off flavors. Adding a campden tablet will aid in that. https://www.morebeer.com/articles/removing_chloramines_from_water.

To prevent scorching of the LME, add it off heat and completely dissolve it, then proceed with a standard boil. The LME should be in there the whole time for most recipes.

  • Thanks. I've got a carbon filter on my water line so that should take care of the chlorine/chloramine according to that link. Any method for santizing other than boiling?
    – HomeBrew
    Jun 18, 2020 at 19:54
  • @HomeBrew There are but you don't want to do them. Just boil and or campden tablets. Jun 18, 2020 at 22:20
  • Most of the chloramines will evaporate in 24h after adding the water to the carboy. To put tap water in a closed container for 24h is a documented way to remove most of the chloramides. Tasting it in a finished product would be surprising, unless your tap water as more than 0,080 mg/L of chloramides (which is the maximum allowed in my city).
    – Philippe
    Jun 19, 2020 at 15:22

Not exactly a veteran myself but I have done a number of extract brews with a partial boil as you describe.

Latest guidelines for such partial boils don't typical call for pre-sanitizing the top-off water. Modern tap water is apparently "clean enough". The pre-boiled method you describe is the only alternative I am aware of. The other is to add all the top off water just after end of boil, the mixing with the near boiling hot partial boil wort apparently does the sanitizing for you. I usually cool first, then top-off.

As for when to add LME, it depends on the recipe. Most extracts I have done call for LME added at start of boil, with some occasionally adding more LME near then end as you call out.

Hope this helps.


I never boil my top-off water, because if it is good enough to drink, it is good enough to make beer. You can do it if you like, but I don't consider it mandatory. Also, I sometimes top-off with bottled water (already treated).

Regarding LME, I usually follow the recipe instructions, but boiling LME (or DME) can cause a caramel-like flavor and increase the color (mailard reaction). The reason to boil is mostly to sanitize it, but it comes sterile when you buy it, so it is not useful unless it is part of the recipe.

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