Brewed various bottle conditioned ales all with the same fault. They taste great at bottling and get better for about 3 weeks to a month, during this period they actually taste fantastic; then they deteriorate quickly with a growing earthy taste, by 2 months they are undrinkable! Tried various sterilising agents and methods, dark bottles, refrigeration, glucose drop primers, decanting off of yeast sediment and resettling before bottling, all with the same result. I've actually stopped brewing because of this but want to restart and get past this issue. Any advice more than welcome :0) p.s. generally they take 7 to 10 days fermentation then 7 settling before bottling.

  • What FVs are you using? What transfer tubes? What exactly is you preferred/most recent sterilisation methodology?
    – Mr_road
    Apr 30, 2017 at 17:03

4 Answers 4


The changes that can happen to your brew over time are caused by a couple different practices. Please note, I don't know your skill level, so I don't know how much you know about brewing. I'm not trying to insult anyone. Just offering information.


As others have mentioned, this is bacteria or possibly wild yeasts. You mention that you have tried several sterilization methods, etc. But you don't list what those are. Here's a basic primer on sanitation:

  • First off, CLEAN. This cannot be overstated. Something cannot be sanitized if it is not clean. For cleaning tubing without a pump, soak in Oxyclean Free or PBW overnight. Make sure your hoses are fully immersed in the solution. (Add the PBW/OxyClean to the water, stir well, then add hoses.) Let sit overnight. This will help remove any film that could be accumulating in your hoses. You need to be able to sanitize UNDER this, and you can't if it's there.
  • Anything that touches your wort AFTER the boil needs to be fully sanitized. Use something simple like StarSan. MIX ACCORDING TO THE DIRECTIONS!! Anything that touches the wort needs to soak in this for at least a few minutes. (Overkill is better than spoilage.) Mash paddles, hoses, fittings, tubes, etc.
  • Don't add water to your brew after the boil. Some people do a partial boil, and if you can't get away from this, there's not much you can do, but the entire volume of liquid really should be boiled. It's just one more place you can add contamination.
  • Are you fermenting in plastic? How long has it been since you replaced those buckets? Even the simple act of cleaning can add micro scratches which allow bacteria to hide. Buckets are cheaper than throwing out multiple batches of beer.
  • Are you doing a secondary fermentation in another vessel? I'd question whether that's really truly necessary. A whole host of potential problems can be avoided just by not doing a secondary transfer, and one of those is contamination.
  • Cool your wort quickly and do it with a lid or other cover on your boil kettle. The longer you take, the more errant bacteria has a chance to get into your beer.
  • Same with bottling. Do it as quickly as possible. Everything that touches your beer should be disassembled and sanitized. Bottles should be completely clean and soaked in Star San, or ran through the dishwasher. (IMO, do not use the dishwasher to clean, but that's just me. I'm not convinced that enough spray gets into the small bottle opening. The dishwasher is for sanitizing, IMO.) Sanitize even your bottlecaps.


This is a little harder to lock down, and it involves your process. Earthy is typically a flavor I connect with sanitation, but I offer these tips in an effort of completeness.

During the Brew Day

  • Use finings to drop as much protein and fatty lipids out of suspension when brewing. I tend to like Whirfloc very much for this.

During Bottling

  • Avoid as much splashing as possible when bottling. Once fermentation has occurred, you want to avoid aeration of wort. Do not pour, use hoses and siphons to transfer. (Keeping in mind all the sanitation stuff above.)
  • Avoid pulling the trub at the bottom of your fermenter into the bottling bucket. Some of the stuff that settles out can stale your beer more quickly.
  • Light probably isn't contributing to earthiness, but is more associated with skunk-smell and -flavor. It should be said, though. For storage of bottles, you want cool and dark.
  • I recommend a cold crash if you can do it. This helps things (potential staling agents) drop out of suspension. A cold crash is quickly dropping the temperature of your fully-fermented beer down to near-freezing. If you're using an s-type airlock, you won't have to worry about sucking back airlock liquid, but you might have issues when using a 3-piece, and almost certainly will if using a tube into a bowl or glass of water.
  • A great way to drop staling agents is using gelatin when the fermenter is COLD (see the above tip on cold-crashing). Gelatin works best when the liquid is cold. From Brulosophy (5 gallon batch size):

...combining 1/2 tsp Knox Unflavored Gelatin with 1/4 cup cool water then microwaving it in short (7 second) bursts until it reached 145-150°F, stirring with the end of a thermometer between each burst.

That's about it. I hope some of these tips help.


If it's contamination by spoilage organisms, then you would hope that refrigeration would slow down the process. Did you try a a taste comparison, such as a blind triangle test? Put a few bottles in the fridge and leave a few out up until the day of the test, when you'll also put all the beers in the fridge (so all tested beers are served at the same temperature.) Have a friend, spouse or well-trained puppy prepare them in groups of 3 - 2 of one kind and 1 of the other - only your friend will know which is which by numbering each bottle and correlating that number to where it was stored. With each flight of 3, taste each and see if you can tell the one that is different and if it is more or less pleasant.

Once all bottles are tasted you'll be able to see if storing in the fridge makes a difference.

I'd be very surprised if it doesn't - oxidation and contamination are the primary causes of beer spoilage and they proceed significantly slower at fridge temperature.


I have been generally fortunate and not had many beers spoil, but I have had a few and it has taken a while to track down the offender each time.

First offender was the bottling tree we were using, we steralised bottles, then but them on the clean tree. It was clean but is was not sterile/sanitised solution for this one was to soak the bottling tree in caustic over night then rinse with Phosphoric acid based no rinse sanitiser before use. That fixed the lactic pick up from the tree.

Second was the joints on the transfer tubes, I was not religiously dismantling my pipes and sterilising them. Solution was as above, dismantle and soak in caustic for about an hour once a month, then rinse in no rinse sanitiser.

Your problem does not sound like these, but instead sound like the falvour development generated by "2-ethyl fenchol", which gives a distinctive earthy/damp soil off flavour. This is generally generated by microbes found in cellars, and penetrates through permeable packaging such as caps.

My first question would be, are you brewing or conditioning or bottling, or storing in a cellar? If so does the cellar smell musty?

Next question are you using tap or ground water? There is a chance that the contamination is not coming from without(cellar) but within the beer(bacterial), if you a rinsing something with water from a ground source, then there is a chance it is picking up biological contamination there.

I hope that helps, any more details you can provide will help narrow this down.


Is it just one style of beer or all that do this?

What you're describing is typical for beers that depend on hop aroma and flavor such as hoppy pales / IPAs going earthy or showing faults once the fresh hop luster falls off after a month or so.

Many styles are best fresh others get better with age. Basically hop dependant styles are best fresh, while malt and ester depended have much better shelf life.

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