Water Bath Canning

Water Bath Canning


onion jam


Water bath canning is a preservation method used only for high-acid foods such as certain fruits and pickles. The high-acid food is placed in jars and covered with boiling water for a set period of time to destroy bacteria and molds and allow the food to be stored at room temperature.


How does it work?

A jar is packed and loosely sealed and placed in a pot of boiling water long enough to bring the food inside to 100 degrees celsius (212F). The heat from the boiling water expands the food which pushes all of the air out of the jar. The jar is then removed from the pot and as it begins to cool it contracts, forming a vacuum seal. This seal keeps all microorganisms out while killing off any that remain in the food.

This method of canning is only safe to be used with tested high-acid recipes.


Step by step guide to water bath canning


Step 1: Gather your tools.

To water bath can you will need:

  • a tested preserving recipe
  • all the ingredients called for in the recipe
  • a boiling water canner or a large, deep pot with a lid and a rack that sits on the bottom of the pot (this stops the jars from sitting directly on the bottom of the pot)
  • glass preserving jars with lids and bands (you must use new lids)
  • jar lifter
  • bubble remover and headspace measuring tool


Step 2: Getting started.

Visually examine your jars for defects. Make sure that there are no chips or cracks around the edge of the jar, otherwise the lid will not seal properly. Also ensure that the jars have no rust on them. If they are rusty and you can not remove the rust then do not can with them. 

You then need to sterilise and warm your jars. There are two ways to do this:

  1. Fill a large saucepan or stockpot with water. Place the jars into the water (fill the jars with water to prevent them floating in the pot). Bring the pot to a simmer. Keep the jars hot until they are ready for use as this will prevent jar breakage due to an abrupt change in temperature.
  2. You may also use a dishwasher to wash and heat jars.

Wash your new lids in soapy water and set aside. Leave bands at room temperature for easy handling.


Step 3: Prepare canner.

Fill your boiling water canner with water. You will need enough water that when you place your jars into the pot they are covered by at least 1 inch of rapidly boiling water.

Turn heat onto medium to begin warming up your canner water.


Step 4: Prepare your recipe.

Follow the instructions of your tested recipe exactly.


Step 5: Fill your jars.

Fill your hot jars one at a time with hot prepared food using a jar funnel.

Measure your headspace and use a plastic bubble remover to remove any excess air. You do this by sliding a bubble remover or rubber spatula between the jar and the food to release trapped air and ensure proper headspace during processing.

Clean rime and threads of jar using a clean, damp cloth or paper towel to remove any food residue.

Place lid on jar and apply band until finger-tip tight.

Place your filled jar into the canner.

Repeat this step until all your jars are filled or the canner is full.

It is useful to have a rack that you can lift and lower into the water, as you can place your jars onto the rack while you are finishing filling the rest of them and then altogether lower them into the water.


Step 6: Process your jars

Place lid on canner and bring water to a full rolling boil. Begin timing and maintain a rolling boil throughout the entire processing period.

Once the time is up turn off the heat and allow to stand for 5 minutes. Take the lid off the canner and allow to stand for a further 10 minutes.


Step 7: Finishing up.

Remove your jars from the canner. Set the jars upright on a towel to prevent jar breakage while they cool. Leave jars undisturbed for 12-24 hours. The bands on the jars should not be re-tightened during this time.

After this time check the lids of seals. The lids should not flex up and down when the centre is pressed. Remove the bands and try to lift lids off with your fingertips. If the lid cannot be lifted then a good seal has been achieved.

Remove the bands at this time and wash your jars in warm soapy water. Dry thoroughly, label and store in a cool, dry, dark place for up to 1 year.



Tips and tricks

  • If a jar doesn’t seal properly after processing then place into the refrigerator and re-process within 24 hours. You may need to use a new lid to ensure a proper seal. Also make sure the jar doesn’t have any cracks or chips that is stopping it from sealing.
  • You can ‘double decker’ your jars in your canner. For example if the bottom of your canner only fits 10 jars then you can place a wire rack on top of these jars and then layer another 10 jars on top of these jars. Make sure that the top of your jars are covered by 1-2 inches of rapidly boiling water though!
  • Syphoning is a common problem with both water bath canning and pressure canning. Syphoning occurs when all of your liquid comes out of your jar either when it is in the canner or when it is cooling on your bench. How to avoid syphoning:
    • ensure that everything is hot. You want hot jars, hot food and a hot canner. There is far less chance of syphoning occurring if everything starts out hot.
    • make sure you are using the right headspace.
    • give all of your jars a thorough de-bubbling before processing.
  • Make sure you are using the correct altitude for your canning. The incorrect altitude could lead to food spoilage.


Now head over to my recipes page and get canning!!