What’s wrong with a plastic carboy?


I am new  to homebrewing and I am reading as much as I can, I see that many people use 6 gallon buckets as there fermenter, others like a glass carboy. My question is why can you not use a plastic carboy? I am guessing because it has flavors that can taint the brew, but if you sanitize enough will it still work? Any info on this would be great, because I can get several plastic ones for free, but I would have to buy a glass one, although not that expensive still it would be good if I could get a free one.

Thanks in advance

Hey gregory,

Problem with buckets can come in a variety of problems. First of all the interior is easy to scratch. Which can lead to infections ask a mold and bacteria which then will ruin anything you are home brewing. No matter how much you think it’s sanitized, ya can still run that risk. Granted a bucket is cheaper but a glass carboy at least you don’t have to worry about scratches on the inside of the glass.
Another problem with buckets is if you have to ferment for extended lengths of time. It’s pretty easy to oxidize a brew in a bucket. Buckets also allow a little oxygen flow slowly over time. Another problem is if the brew is infected, you cannot see it. Yet again, a problem can arise from the lid not being properly sealed. That’s a bucket in a nutshell.
Glass carboys can be dangerous if handled with damp or wet hands. They can also break if you are not careful. It has all the benefits from seeing the brew fermenting to the proper seal on the 3 way valve that lets out the co2 being formed as a by-product. They also cost more than a bucket but they also have a longer life expectancy than a bucket. So in your brew time you may end up having to get 30 buckets versus only 1 glass carboy.
In reality, a 6 gallon bucket will work but you really want one that is 6.5 gallons. You will ask why. Its because of the fermentation process can get very explosive meaning there is a lot of action going on inside which the yeast will cause bubbles and rise on top of the wort. Wort being what is turned into the final product. I’ve had fermentation process that a 7 gallon bucket couldn’t contain so a 6 gallon won’t either. But that is from my personal experience. I hope all this helps. If not, just pm me for more details.

I was making a batch of wine using a bucket for primary fermentation. I opened the lid (that had a burper), to check the SG (sugar level)… and after I shut it, the stuff really took off. Took longer, but would recommend doing this way as its good aseptic practice. BTW, buckets are free, drill a hole, and plug with bung. Works like a charm!

My understanding is the same as Darren’s, that plastic is harder to disinfect than glass, and more likely to contaminate your product. Not sure what this says about ancient methods, which involved clay, wood and cow stomachs and such. I think I’ll pass on trying some of those methods. smile

1 gallon glass jugs can be pretty easy to obtain–just buy a jug of apple juice at the grocery! Be sure to sanitize well before using, though.

I’m not sure how to cheaply get bigger glass carboys, though. Do any water companies still use 5 gal. glass jugs? Any of them not require returning the bottles? Most I’ve seen now use plastic, but the plastic they use I’d be inclined to trust, since their business depends on not getting impurities in your water.

you will have to use glass i m afraid coz if you need to prevent from mole and bacteria. So a little investment may be involved but the results will got better! I primary in 1/2 bbl sankey kegs. I secondary in 5 gal plastic carboys. I have a wall covered with ribbons. Plastic pails are fine for primary but you have to be careful not to scratch them.


There is a difference between, a plastic carboy drinking water(5gal). and a Plastic carboy(5gal) made of PET. Poly..something. It is a non-barrier plastic, meaning oxygen can not transfer through the plastic and oxidize
your beer. A oridnary 5gal carboy for drinking water will impart taste and oxygen over time. So if you are going to use plastic carboys or bottles make sure they are PET. It will say on the bottom.

Brew on..

There may be a difference but I still stand by my water bottles. Cheap and good. The proof is on my wall. A cider I took best of show with aged in plastic water carboys for 6 months. I have had judges pick up other unrelated flaws but never oxidation.