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Plastic vs glass vs stainless fermenters for homebrew

Buckets and PET are light and cheap, glass is clear and scratch-proof but breakable, stainless lasts and can hold pressure. Here is how they compare on paper.

Updated November 2026 · 6 min read

Plastic fermenters with airlocks beside a small stainless conical fermenter
Home Brew Ohio 6.5 Gal Fermenting Bucket with Lid and AirlockFerMonster 6 Gal Fermenter with Econolock and #10 StopperSpeidel 20L HDPE FermenterKegLand FermZilla All Rounder 30L PET FermenterBrewer’s Best 7.9 Gal Fermenting BucketSs Brewtech Brew Bucket Stainless Fermenter, 7 Gal
Photo: paulmed, CC BY-SA 2.0, via Flickr
The short version
  • Plastic buckets (HDPE, polypropylene) are the cheapest, lightest primary fermenters; they scratch, so clean with soft cloths only.
  • PET carboys and fermenters (FerMonster, FermZilla) are clear, light and less oxygen-permeable than buckets; the FermZilla All Rounder kit is rated 2.5 bar (36.2 psi) for pressure fermenting.
  • Glass doesn't scratch or stain, but carboys break and cut. Carry them by the base in a carrier and never pour hot wort into cold glass.
  • Stainless (Ss Brewtech, Spike, Northern Brewer) lasts for decades and takes hot cleaning; it's opaque and costs the most.

Plastic vs glass vs stainless fermenter choices come down to five things: headspace for your batch size, how easy the vessel is to clean and sanitize, how much oxygen gets in, whether it can hold pressure, and how safe it is to move when full. A full 5-gallon (19 L) batch weighs over 40 lb, so the last point matters more than it sounds.

This page compares the three materials using the listed volumes, materials and pressure ratings of fermenters from Home Brew Ohio, FerMonster, Speidel, KegLand, Brewer's Best, Ss Brewtech, Spike Brewing, Northern Brewer, VEVOR, North Mountain Supply, Kegco and Eagle. Browse them all in the fermenters and temperature control hub.

Plastic (HDPE buckets and PET)

Light, inexpensive, wide openings; PET options can hold pressure

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vs

Stainless steel

Durable, easy to clean hot, ports for valves and thermometers

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Picks from each side

Plastic (HDPE buckets and PET)

Stainless steel

Plastic vs glass vs stainless at a glance

HDPE / PP bucketPET carboy / fermenterGlass carboyStainless
Weight empty✓ Light✓ Light✗ Heavy~ Moderate
Breakage risk✓ Low✓ Low✗ Shatters, cuts✓ Very low
Scratches✗ Easily~ Avoid abrasives✓ No✓ Resists
See the beer✗✓✓✗
Oxygen ingress~ Higher; lid seal matters✓ Low✓ Very low✓ Very low
Hot cleaning~ Check the maker's limit✗ Warm only~ No thermal shock✓
Pressure capable✗~ FermZilla only (2.4–2.5 bar)✗~ Some models (e.g. 15 PSI)
Wide opening for cleaning✓~ FerMonster wide mouth✗ Narrow neck (Kegco wide mouth excepted)✓
Lifespan~ Replace when scratched~ Years with care✓ Indefinite if unbroken✓ Decades

Source: Listing data for the fermenters shown; Beer & Brewing homebrew safety

Headspace: which size for a 5-gallon batch?

Active fermentation throws foam (krausen) a few inches high. A primary fermenter needs room above the beer, or you'll need a blow-off tube. Here is the headspace left over a 5-gallon batch in common listed sizes:

Headspace over a 5 gal batch

Listed vessel volume minus 5 gal

5 gal glass carboy: 0 gal0 gal5 gal glass carboy6 gal FerMonster PET: 1 gal1 gal6 gal FerMonster PET6.5 gal bucket or carboy: 1.5 gal1.5 gal6.5 gal bucket or carboy7 gal Ss Brew Bucket: 2 gal2 gal7 gal Ss Brew Bucket7.9 gal FermZilla 30L: 2.9 gal2.9 gal7.9 gal FermZilla 30L
Source: Listed volumes: Eagle FE320, FerMonster, Home Brew Ohio, Ss Brewtech, KegLand

A 5-gallon glass carboy is a secondary or bulk-aging vessel for 5-gallon batches, not a primary. For primary fermentation, 6.5 gallons or more is comfortable; 6 gallons works with a blow-off tube on vigorous yeasts.

Pressure ratings: which fermenters can hold pressure?

Pressure fermenting (spunding) lets you ferment warmer with fewer esters, carbonate in the fermenter and transfer to a keg without oxygen. Only vessels with a stated pressure rating and a relief valve are suitable.

Listed working pressure

PSI; buckets and glass carboys have no pressure rating

FermZilla All Rounder 30L kitFermZilla All Rounder 30L kit: 36.2 psi36.2 psiFermZilla Tri-Conical 27LFermZilla Tri-Conical 27L: 34.8 psi34.8 psiVEVOR 30L stainlessVEVOR 30L stainless: 15 psi15 psiBucket or glass carboyBucket or glass carboy: 0 psi0 psi
Source: KegLand and VEVOR listings (2.5 bar and 2.4 bar converted at 14.5 psi per bar)

Never pressurize a vessel beyond its rating, and never pressurize a bucket, a PET water-style carboy or glass. FermZilla kits ship with a pressure relief valve; keep it in place. Spunding valves such as the KegLand BlowTie set the pressure you hold. For carbonation targets in the keg afterwards, use the keg carbonation chart.

CO2 cylinders and pressureKeep cylinders upright and secured, and always use a CO2-rated regulator (US CO2 tanks use the CGA 320 valve fitting); never connect a cylinder straight to a keg. Store tanks cool and away from heat. CO2 displaces oxygen and collects low: ventilate, close the tank valve and leave the room if a tank leaks. Never exceed a fermenter’s or keg’s rated pressure.Source: Kegco: Everything you need to know about CO2; OSHA hazard bulletin on CO2

Glass carboys: clear, inert and fragile

Glass doesn't scratch, stain or hold odors, and it lets almost no oxygen through, which is why winemakers and lager brewers still use it for long aging. The trade-off is weight and breakage: Craft Beer & Brewing calls a wet, full glass carboy an accident waiting to happen and says to use a good handle and always support the bottom, and the CPSC recalled Saxco carboys for laceration hazards. One listed set (Suzile) gives a 104°F (40°C) maximum, a reminder that glass and hot liquid don't mix.

Straining fruit into a large green glass demijohn on a kitchen table
Glass shows what's happening, but it is heavy and fragile.Photo: F Ceragioli, CC BY-SA 4.0, via Wikimedia Commons
Glass carboys breakGlass carboys can break and cut. Use a good carboy handle and always support the bottom when you move a full one; a crate or carrier under the base helps on slippery floors. Never pour hot wort into cold glass. PET and stainless avoid the risk.Source: Craft Beer & Brewing: Homebrew safety

If you choose glass, add a carrier strap (Brew Hauler, HomeBrewStuff) and set the carboy in a milk crate or on a rubber mat. Never carry a full carboy by a neck handle alone.

Cleaning and sanitizing each material

  • Plastic buckets: soak with an oxygen-based cleaner such as PBW per the label, wipe with a soft cloth, then sanitize. Scratches can harbor bacteria; replace a bucket that is deeply scratched.
  • PET: no abrasive brushes and no hot water beyond the maker's limit. Wide-mouth designs (FerMonster) let you reach in by hand.
  • Glass: a carboy brush and a jet washer reach the shoulder. Let hot glass cool before adding cold liquid, and vice versa.
  • Stainless: takes hot cleaner and scrubbing pads made for stainless; avoid chlorine bleach left in contact, which can pit steel.

Cleaners clean; sanitizers sanitize. Star San is an EPA-registered no-rinse sanitizer at label dilution, while PBW and OneStep are cleaners.

Chemicals: label directions onlyUse sanitizers, cleaners, acids and salts only at the dilution and contact time on the label. Wear eye protection with acids and powders, add acid to water, keep them away from children and food prep. Star San is EPA-registered (Reg. No. 65001-1) as a no-rinse sanitizer at label dilution.Source: EPA Star San label

Who should choose which

Fermenter material by situation

SituationPlastic / PETGlassStainless
First batch✓ Bucket~~
Kids or pets around, tile floors✓✗✓
Long aging (wine, mead, lager)~ PET✓✓
Pressure fermenting✓ FermZilla✗~ Rated models
Hot cleaning and decades of use✗~✓
Watching fermentation✓ PET✓✗
Glycol or cooling-coil upgrades later~✗✓ Ports on conicals

Choose plastic (a 6.5–7.9 gallon bucket or a FerMonster PET carboy) for a first batch and light, cheap handling. Choose a FermZilla if pressure fermenting is on your list. Choose glass for long aging if you can move it safely. Choose stainless if you want a vessel for life, hot cleaning and ports for valves, thermowells and cooling. Pair any of them with a controller from the temperature control and summer page.

Mistakes to avoid

  1. Primary fermenting 5 gallons in a 5-gallon carboy. No headspace means a clogged airlock and krausen on the ceiling; use 6.5 gallons or a blow-off tube.
  2. Scrubbing plastic with abrasive pads. Scratches are hard to sanitize.
  3. Pressurizing an unrated vessel. Only vessels with a listed pressure rating and a relief valve.
  4. Moving full glass by the neck. Carry it from the base in a crate or carrier.
  5. Opening the lid every day. Each opening lets oxygen and microbes in. Log gravity readings in the brew-day log and check fermentation progress with the ABV calculator at the end instead.
Verdict

Plastic buckets and PET carboys are the practical default: light, cheap, easy to handle, and in the FermZilla's case pressure-rated. Glass suits long aging if you can store and move it safely. Stainless is the long-term buy for brewers who want hot cleaning, ports and a fermenter that never wears out. Whatever you pick, leave at least a gallon of headspace for a 5-gallon primary.

How we chose

We compared listed volumes, materials and pressure ratings for the fermenters shown, plus safety guidance from Craft Beer & Brewing and the CPSC. We did not ferment in these vessels or measure oxygen ingress; material traits are general properties, not product tests.

ABV calculatorWork out ABV from OG and FG with the standard and high-gravity formulas, hydrometer temperature correction,…Keg carbonation chart and PSI calculatorKeg carbonation chart and calculator: regulator PSI by beer temperature and CO2 volumes, with an altitude…Printable brew-day log and recipe sheetFree brew-day log: record recipe, water and salts, mash, gravities, yeast, fermentation temperatures,…

Questions

Plastic vs glass fermenter: which is better for beer?
Both make good beer. Plastic buckets and PET are lighter and won't shatter; glass doesn't scratch and lets in less oxygen, which matters most for long aging. For most 5-gallon ales, a 6.5-gallon bucket or PET carboy is the practical choice.
Are plastic fermenters safe?
Food-grade HDPE, polypropylene and PET fermenters made for brewing are designed for this use. Several listings state BPA-free food-grade plastic. Replace a fermenter that is deeply scratched or warped.
How full should a fermenter be?
Leave at least about 1–1.5 gallons of headspace over a 5-gallon batch for krausen, or fit a blow-off tube. That's why 6.5-gallon buckets and carboys are the standard primary size.
Is a stainless steel fermenter worth it?
It's worth it if you want a fermenter for decades, hot cleaning, and ports for a racking arm, thermometer or cooling. It doesn't make the beer better on its own, and you can't see the fermentation.
Can I pressure ferment in a plastic fermenter?
Only in one designed and rated for it, such as the PET FermZilla (listed at 2.5 bar or 36.2 psi on the 30L kit) with its relief valve in place. Never pressurize a bucket or a glass carboy.
Why do glass carboys break?
Impacts, thermal shock from hot or cold liquid, and stress at the neck when carried by a handle. Carry carboys by the base in a carrier and never pour hot wort into cold glass.

Sources

  1. Craft Beer & Brewing: Homebrew safety
  2. CPSC: Saxco International recalls carboys due to laceration hazard
  3. BYO: Caution, homebrewers at work
  4. EPA: Star San label (Reg. No. 65001-1)
  5. John Palmer, How to Brew (online edition)