Clean a Carboy in 4 “Easy” Steps

Consider a multi-pronged offense for cleaning those stubborn carboys—one that adapts to the realities of a suboptimal situation.

Dave Carpenter Sep 20, 2015 - 4 min read

Clean a Carboy in 4 “Easy” Steps Primary Image

It was never meant to come to this. Last time would be THE last time, you swore it. But here you are once again, facing down another stubborn ring of fermentation detritus mockingly clinging to the inside of a carboy.

The previous day settles in your head like summer fog at the Golden Gate. You remember brewing. You remember racking. You remember reading a text message, leaving the house, and sitting down at the craft-beer bar. A crumpled receipt in your wallet fills in the rest, and now it’s time to pay the piper, both in ibuprofen and in trub removal.

Let’s not kid ourselves: Cleaning a carboy will never rank highly on your list of pastimes. At best you’ll squeak through it and breathe a sigh of relief when things go more smoothly than expected. But the well-founded anxiety is always there because for every straightforward cleanup, at least two will try your patience.

I wish there were a safe, simple, foolproof solution that’s guaranteed to work every time, some kind of “Don’t wait! Call now!” late-night TV miracle product. There isn’t. So until Ron Popeil delivers the goods, we need to consider a multi-pronged offense that adapts to the realities of a suboptimal situation. Thus, I give you my four-step plan for cleaning those stubborn carboys.


Step 1

Warm water and a trusty cleaner such as PBW or OxiClean is a great opening volley. A gentle shake of the carboy should remove the first layer of crust, and if you’re lucky, the big bottle battle stops here. You may need to do this a few times, rinsing well in between.

Step 2

If warm water and a shake or six don’t get you there, then it’s time for a long soak. First, fill your carboy with a solution of up to 4 fluid ounces (118 ml) of household bleach per 5 gallons (19 liters) of water, and let it sit overnight—the longer, the better. Then, soak yourself in a hot tub—the longer the better, but, for best results, not overnight.

Step 3

If you’re still left with a small ring of gunk, then it’s time to bust out the carboy brush and crank up the elbow grease. Glass can take some abrasive abuse, but it’s not a good idea to do this with plastic carboys because they’ll scratch. Some of us, however, have been known to throw caution to the wind in a fit of frustration and do it anyway. At least wrap the bristles with a sock or a chamois cloth before going in.

Step 4

If, after all of this, the stuff still won’t come off, get a new carboy. Your time is worth more than this.

If you do buy a new carboy, spring for one of those new wide-mouth models. But they may only be around for a limited time, so act now!

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