Single clean glass jar with lid

When making homemade jams, chutneys, craft beers, or wines, sterilising your glass jars and bottles is essential. Without proper sterilisation, harmful bacteria can spoil your creations, affect taste, and shorten shelf life.

As autumn arrives and kitchens fill with the scent of chutneys and spiced plum jam, it’s the perfect time to make sure your jam jars and bottles are properly prepared. The good news? Sterilising glass containers at home is simple, and you don’t need any specialist equipment.

In this guide, we’ll show you three easy ways to sterilise glass jars and bottles, along with extra tips to keep your containers safe, clean, and ready to use for the season ahead.

Why Sterilise Glass Jars and Bottles?

  • Prevents spoilage and mould growth.

  • Keeps food and drink fresh for longer.

  • Maintains flavour and quality.

  • Essential for home canning, preserving, brewing, or winemaking.

Glass jars being steralised in boiling water

Boiling Water Sterilisation

Boiling is the most traditional and effective way to sterilise jars and bottles. It requires minimal equipment and guarantees thorough sterilisation – making it ideal for small batches of autumn chutney or seasonal fruit preserves.

What You’ll Need:

  • Glass jars or bottles
  • A large pot with a lid
  • A rack or cloth to line the bottom of the pot (to prevent the glass from cracking)
  • Tongs or a jar lifter
  • Water

Step-by-Step Method:

  1. Wash thoroughly – Clean the jars and bottles with hot, soapy water. Scrub with a brush, then rinse well.

  2. Prepare the pot – Line the base with a rack or folded cloth, then fill with enough water to cover your jars.

  3. Submerge jars – Place jars into the pot, ensuring they’re completely submerged. Add water inside the jars to prevent floating.

  4. Boil – Bring to a rolling boil, cover with the lid, and maintain for 10 minutes.

  5. Remove and dry – Carefully lift jars out with tongs and place on a clean towel to air dry.

This method is great for small to medium batches, but does require some time and attention.

an empty oven with the door open and light glowing

Oven Sterilisation

Oven sterilisation is an excellent alternative to boiling, especially if you need to sterilise a large batch of jars simultaneously. It’s efficient and can be particularly useful if you’re already using the oven for other preparations. This method provides dry heat that is effective in killing potential contaminants, making it suitable for longer storage durations.

What You’ll Need

  • Glass jars and bottles
  • An oven
  • A baking sheet
  • Oven mitts 

Method

  1. Clean Thoroughly: Wash the glass jars and bottles thoroughly with hot, soapy water. Scrub the insides using a bottle brush to ensure all residue and dirt are removed. Rinse thoroughly to eliminate any soap residue.
  2. Preheat the Oven: Set your oven to 225 degrees Fahrenheit (about 110 degrees Celsius). It’s important not to exceed this temperature as higher heat could damage the glass.
  3. Prepare the Jars: Arrange the clean, empty jars on a baking sheet, making sure they do not touch each other to prevent them from cracking due to uneven heating.
  4. Sterilise: Place the baking sheet with jars in the preheated oven. Sterilise the jars for at least 20 minutes. This duration ensures that all harmful organisms are effectively killed.
  5. Remove and Cool: Carefully remove the baking sheet from the oven using oven mitts. Let the jars cool on the baking sheet in a safe, undisturbed area until they reach room temperature.

This dry-heat method is especially useful if you plan to store preserves or bottled drinks for longer periods over the winter.

glass-jars-dishwasher

Dishwasher Sterilisation

Dishwasher sterilisation is a convenient and efficient option for those who have a dishwasher with a hot wash and dry cycle. It’s especially practical for busy individuals or for those who are processing a large number of jars at once, ahead of Christmas gifting or making homemade drinks like sloe gin. This method uses the dishwasher’s built-in heat and steam to clean and sterilise, making it a hands-free, low-effort choice for ensuring your jars and bottles are ready for use. 

What You’ll Need

  • Glass jars and bottles
  • Dishwasher
  • Dish detergent (optional)

Method

  1. Load the Dishwasher: Place your clean jars and bottles in the dishwasher. Ensure that they are spaced well apart to allow the hot water and steam to circulate freely around each jar, providing thorough sterilisation.
  2. Set to Hot Wash Cycle: Select the hottest wash and dry cycle available on your dishwasher. This setting will use high temperatures to clean and sterilise the jars effectively. If your dishwasher has a “sanitise” setting, use it, as it is designed to achieve a higher level of sterilisation.
  3. Run the Dishwasher: Start the dishwasher and let the cycle complete. The combination of hot water and steam during the washing and drying phases will sterilise the jars.
  4. Remove and Use: Once the cycle is finished and the jars have cooled slightly but are still warm, remove them from the dishwasher. For the best sterilisation results, use the jars while they are still warm.

Dishwasher sterilisation is particularly useful if you are preparing jars for canning and have other tasks to manage; it allows you to multitask efficiently. Plus, it’s an excellent method for those seeking a straightforward, automated way to ensure their jars are impeccably clean and ready for filling.

Additional Tips

  • Always handle sterilised jars with clean hands, or consider wearing gloves to keep them sterile.
  • If you’re filling the jars with food for preservation, ensure that the food is prepared and ready to be jarred as soon as the jars are sterilised.
  • Never pour cold contents into a hot jar, as this can cause the glass to shatter.

Frequently Asked Questions

Sterilised jars don’t stay sterile forever. Once they’re removed from heat and exposed to the air, bacteria can start to settle back on the surfaces. If left empty and uncovered, they’ll only remain reliably sterile for a few hours.

If you’re using the oven method, you can keep jars inside the switched-off oven with the door closed for up to 24 hours. With boiling or dishwasher methods, you can leave them upside-down on a clean towel and cover them with a tea towel to help keep dust and particles away, but it’s best to fill them as soon as possible.

In short: always plan your sterilisation around your recipe. Have your jam, chutney, or brew ready to go, and fill the jars straight away while they’re still hot.

A dishwasher alone may not be enough. Standard wash cycles don’t get hot enough to kill all bacteria; they’ll clean but not sterilise.

If your dishwasher has a “sanitise” or high-heat drying cycle (usually 70°C or higher), then it can be used as a sterilisation method. The key is temperature: the hotter the cycle, the more effective it will be.

If you’re unsure, you can run jars through the dishwasher to clean them, then finish them off in the oven for 10–15 minutes. This gives you the convenience of the dishwasher with the reassurance of full sterilisation.

  • Sanitising lowers bacteria and microbes to a safe level, think of wiping down a work surface with antibacterial spray. It’s clean enough for everyday use but not foolproof for long-term food storage.
  • Sterilising goes further: it kills all microorganisms. This is what prevents mould from growing on your jam or bacteria from spoiling your beer.

For short-term storage, sanitising might be enough. However, for preserves, winemaking, or any food stored for weeks or months, sterilisation is essential. It’s the difference between safe, long-lasting results and jars that spoil quickly.

Yes — glass jars are designed to be reused, and it’s one of the reasons they’re such a sustainable choice. But not every jar is suitable:

  • Check for damage: Chips and cracks can cause jars to break under heat or leak once filled. Discard any damaged jars.
  • Inspect the lids: Metal lids often have a single-use seal. Once the seal has been broken, the lid won’t provide an airtight closure. For preserves, you’ll usually need new lids even if the jar itself is fine.
  • Watch for smells or stains: Some jars absorb strong odours (like curry sauces or pickles). If the smell lingers even after washing, it could affect your new batch.
  • Consider jar type: Commercial jars (like supermarket sauce jars) can be reused for some home projects, but they’re not always made to withstand repeated boiling or oven sterilisation. Purpose-made preserving jars are more reliable.

By checking each jar carefully and pairing them with new lids where needed, you can safely reuse glass jars again and again. Reusing jam jars for new seasonal recipes like spiced plum jam is a great way to minimise waste. 

Only use heat-tolerant glass designed for sterilisation. Clear or speciality preserving bottles work best and avoid thin or decorative types that may crack. Check out our Ultimate Guide to Choosing the Right Glass Bottle for full details on selecting the safest options.

Yes, sterilise them a few days before filling. Just keep them sealed and in a clean environment until you’re ready to add your festive chutneys, jams, or cordials.

It’s not always necessary for dry ingredients, but a quick sterilisation helps keep the jars spotless and ensures the gift looks professional.

Related posts