How To Clean and Sanitize a Plastic Fermenter (Carboys and Buckets)

If you’ve decided to use a plastic fermenter for home brewing, you should know the best practices to maintain clean and sanitary equipment. Whether you use a plastic carboy or a fermentation bucket, there are a number of critical steps that can keep you safe and prevent your beer from developing off-flavors during brewing.

Clean plastic fermenters (carboy or bucket) by rinsing off excess dirt and debris, soaking and washing with a brewing cleanser such as PBW, and rinsing with cold water. To sanitize a plastic fermenter, soak or spray with a no-rinse brewing sanitizer such as Star San soon before brewing a batch of beer. Avoid scratching the plastic during cleaning.

Read on to learn more about the specific methods and products you will need to keep your plastic fermenter sanitary: 

How to clean plastic brewing equipment

Cleaning plastic fermenters requires a bit more care than you would use with a glass carboy; because plastic is porous and can scratch easily, you will need to be careful to avoid abrasive cleaning products or over-scrubbing. Instead of using a typical carboy brush, the best choice is to use a dish wand or a brush specifically designed for plastic carboys. It is also best to soak your plastic fermenter overnight with a brewing cleaner such as PBW to reduce the amount of scrubbing needed. Once your equipment is done soaking, you can scrub it gently with a non-abrasive, all-purpose cleaner before rinsing with clean water.

No matter how gently you clean your equipment, it is a smart idea to occasionally replace your plastic fermenters. Since plastic is naturally porous, even unscratched plastics can hold onto odors and bacteria over time. You can extend the lifespan of your equipment by cleaning it immediately after brewing, treating it with care, and consistently sanitizing it after cleaning, but even under perfect conditions plastic fermenters should be replaced as needed. 

So to recap, when cleaning your plastic brewing equipment: 

DO: 

  • Clean immediately after use.
  • Soak overnight with a PBW cleaner to remove as many solids as possible without scrubbing. 
  • Scrub gently with non-abrasive tools designed specifically for use on plastic.
  • Frequently replace plastic fermenters

DON’T:

  • Over-scrub your fermentation, even with appropriate brushes.

What do you clean plastic fermenters with?

There are a number of tools and chemical agents you will need to clean your plastic fermenters. The main piece of hardware you should look for is a good dish wand or bottle brush specifically designed for use on plastics. These brushes will be made of softer material and will not feature metal components that would scratch your fermentation bucket or PET carboy.

Next, you’ll want some cleaner: warm, soapy water is a great choice, but you can also invest in a dedicated all-purpose cleaner, and a PBW cleaner for best results.

Finally, you’ll need access to clean water and a place to drain your fermenter.  

How to sanitize plastic brewing equipment

Now that your plastic fermenter is clean, it is time to sanitize your equipment. While cleaning removes visible particulate matter, it leaves behind microbes that are resistant to regular cleaners.

By sanitizing your equipment using either a chemical agent or hot water between 170 and 180° Fahrenheit, you will be able to kill off any harmful bacteria that remain after the cleaning process. Before you move on to sanitization though, make sure you’ve cleaned properly: organic matter coming off the cleaner can interact with sanitizing solutions and reduce their effectiveness.

Because plastics can retain a significant amount of bacteria after sanitization through hot water alone, I recommend using a chemical disinfectant solution.

You can purchase a commercial sanitizer like Star San, or make your own by mixing 2 tablespoons of chlorine bleach (unscented) and testing with a chlorine test strip. From there, you will want to allow the sanitizer to remain in contact with your equipment for an extended period of time; sanitizers do not kill bacteria immediately and require time to do their job properly.

When Sanitizing your equipment, there are a few recommendations to keep in mind.

First, it is important that you let your equipment air dry. Using a sponge or hand towel can deposit bacteria back onto your equipment, which would defeat the purpose of sanitizing it in the first place.

Second, do not use hot water with chemical sanitizers. While hot water is a valid way to disinfect your equipment, high temperatures can decrease the effectiveness of bleach and other sanitizers, so keep your sanitizer solution at room temperature for best results.

So, to review:

DO: 

  • Make sure you remove all visible organic matter during the cleaning process before sanitization.
  • Let your sanitizer stay in contact with your equipment for an extended period of time.
  • Use a chemical sanitizing solution for plastic brewing equipment.

DON’T:

  • Use hot water with chemical sanitizing solutions.
  • Hand dry your equipment.

What do you sanitize plastic fermenters with?

There are a number of chemical solutions you can use to sanitize your plastic fermenters. You can use Star San, a popular phosphoric-acid-based sanitizer, or any number of iodine-based or peroxide-based sanitizers. You can also purchase chlorine bleach to make your own sanitizer by mixing 2 tablespoons of bleach with one gallon of water.  

As mentioned above, if you don’t have any chemical sanitizers, you can use hot water to sanitize your solution instead of using chemicals. Chemical sanitizers are the preferred option for plastics though, so it’s a good idea to invest in one of the sanitizing options listed here.

How to clean and sanitize a plastic fermenting bucket

Here’s a step-by-step guide on how to clean and sanitize your plastic fermenting bucket. Remember to start this process right after you empty the bucket to prevent bacterial growth on the plastic’s surface.

1 – Separate all parts.

To be able to sanitize your fermentation bucket thoroughly, you’ll need to be sure to separate all parts: pull out the airlock and unscrew the lid so that the cleaning and sanitizing solutions can reach all parts of your equipment.

2 – Wipe down the inside of the bucket to remove any particulate.

Wipe down your bucket with a clean sponge or dish towel to remove as much residue as you can.

3 – Fill with PBW Cleaner & Soak overnight.

Fill your fermentation bucket with PBW cleaner and let it soak overnight to pull off any remaining residue stuck to the sides of the bucket.

Dump the PBW cleaner.

4 – Gently scrub down your bucket.

Scrub the sides of your bucket with warm, soapy water and a brush specifically designed for use with plastic containers. Don’t overwork your bucket: if your PBW cleaner worked properly, any leftover organic material should come off very easily.

5 – Rinse with clean water. 

Rinse your container with clean water to remove the soapy water along with any remaining residue you scrubbed off. 

6 – Fill with a sanitizing solution and let sit to allow the solution to kill bacteria

Now it’s time to sanitize: fill your bucket with a sanitizing solution of your choice and let it sit for 5-10 minutes. The longer you leave your equipment in contact with a sanitizer, the better.

7 – Empty container and let it air-dry

Finally, you’ll want to drain the sanitizer from your bucket. Remember to let your equipment air-dry so you don’t reintroduce bacteria with your sponge or dish towel. Once your bucket is completely dry, it’s ready for your next project!

How to clean and sanitize a plastic carboy

Cleaning a plastic carboy is pretty similar to cleaning a fermenting bucket. Here’s how to make sure your PET carboy stays clean and sanitary:

1 – Remove any large particular remaining in the carboy.

If you have a carboy brush specifically designed not to scratch a plastic PET carboy, use it to remove any large particulate prior to cleaning the fermenter chemically.

Otherwise, you can fill the carboy with water and shake it to dislodge larger particles stuck to the inside walls.

2 – Fill with PBW Cleaner & soak overnight.

Fill your fermentation bucket with PBW cleaner and let it soak overnight to pull off any remaining residue stuck to the sides of the bucket. Dump the PBW cleaner.

3 – Gently scrub down your carboy.

Scrub the sides of your carboy with warm, soapy water and a carboy brush specifically designed for use with plastic PET carboys. Don’t overwork your carboy: if your PBW cleaner worked properly, any leftover organic material should come off very easily.

Once again, if you do not have a carboy brush designed for use with plastic fermenters, you can fill your carboy with soapy water and shake it, though this will be less effective.

4 – Rinse to remove any organic material

Rinse your container with clean water to remove the soapy water along with any remaining residue you scrubbed off. 

5 – Fill with a sanitizing solution and let sit to allow the solution to kill bacteria

Fill your carboy with a sanitizing solution of your choice and let it sit for 5-10 minutes. The longer you leave your equipment in contact with a sanitizer, the better.

6 – Empty container and let it air-dry

Drain the sanitizer from your carboy. Let your equipment air-dry so you don’t reintroduce bacteria with your sponge or dish towel. Once you let your carboy dry completely, you’ll be ready to brew your next batch!