Preserve your favorite produce year-round by mastering the basics of water bath canning (aka boiling-water canning). We'll take you through the process step-by-step and share some of our tips for choosing and using basic canning supplies. You'll be a canning connoisseur in no time!
Water bath canning is probably what you think of first when you want to can produce for later, but it's not meant for every food. Because water bath canning processes food at a lower temperature than a pressure canner, it should only be used for foods with naturally high acidity, like many fruits (and tomatoes). Of course, if you're set on water bath canning your veggies, it is possible, you'll just need to raise their acidity by pickling them in vinegar or adding lemon juice. But to keep your food safe to eat, only use a water bath canner when your recipe specifically calls for it, and always follow your recipe's instructions for mixing up pickling liquid or adding lemon juice to each can. We'll teach you the basics of water bath canning so you can get started today!
Essential Canning Rules
Follow these rules exactly to ensure food safety and success when canning at home:
- Know which canner to use: The water bath canner, basically a big pot with a lid and a rack in the bottom, is used for high-acid foods (like many fruits), which naturally resist bacteria growth. If it's time to add a canner to your collection of essential kitchen tools, check out this water bath canner ($99.95, Williams Sonoma). Pressure canners are used with low-acid foods (like veggies or meat) and recipes that are especially prone to harboring harmful microorganisms. Take a look at this Zavor pressure canning set ($149.99, Bed Bath & Beyond) for all the supplies you need. They heat food hotter than water bath canners. Recipes will specify which type of canner is appropriate.
- Choose the right jars: Use jars made specifically for canning such as these Ball mason jars ($10.99, Target). Don't use glass jars from purchased food, even if they look like canning jars. Don't use jars that look different from the canning jars currently on the market. And avoid jars with chipped edges because that can affect the seal. Use the jar size specified in the recipe. Even though vintage canning jars may look cute, don't use them for canning either, as they can easily crack or chip while processing.
- Use lids properly: Use the special two-piece lids manufactured for canning. You can reuse rings, but do not reuse lids, which have a sticky compound that seals the jar. Don't screw on lids too tightly or they won't create a vacuum seal. Heat the lids in very hot but not boiling water or the compound won't seal. Test for sealing on each jar after it has cooled.
- Choose the right recipe: Modern canning recipes are safer than those from even 20 years ago. Foods may be processed longer or hotter. Always use tested recipes from reliable, current sources, and follow the recipe exactly. Don't alter ingredients. Alterations can compromise food safety.
- Keep it clean and keep it hot: Keep everything scrupulously clean. Wash and sterilize jars. Pack hot food into hot jars one at a time rather than assembly-line style. Take only one sterilized jar out of the canner at a time. As soon as it is filled, place it back in the simmering water in the canner.
Water Bath Canning Basics
Water bath canning, also called boiling-water canning or hot-water canning, is used for fruits, tomatoes, salsas, pickles, relishes, jams, and jellies with high acid (and low pH). It's an easy setup that you can mimic if you don't have an actual canner. It's just a large pot with a rack at the bottom to set the jars on. The rack allows water to flow beneath the jars for even heating. It usually also has handles that allow you to lower and lift the jars easily into and out of the hot water. When you're using a water bath canner, pack food into canning jars by the raw-pack (cold-pack) or hot-pack method.
Raw Packing: In raw packing, uncooked food is packed into canning jars and covered with boiling water, juice, or syrup.
Hot Packing: In hot packing, food is partially cooked, packed into jars, and covered with cooking liquid. The following guidelines apply to both methods.
Water Bath Canning Step-by-Step
Once you're up to speed on the canning basics and know for sure that water bath canning is the correct method for you, here's how to get started.
- Wash canning jars in hot, soapy water, and rinse them thoroughly. Place washed jars in the water bath canner or other deep pot. Cover with hot tap water and bring to simmering over medium heat. Let jars simmer 10 minutes, then keep them hot in the simmering water until you're ready to fill each one. When you are ready to fill, remove one sterilized jar from the water and place it on a clean kitchen towel to prevent slipping.
- Place lids in a bowl and pour some hot water from sterilizing pot over top; do not boil the lids. (Screw bands do not need to be sterilized, they never touch food.)
- Most canning racks hold at most seven pint or quart jars, so prepare only as much food as needed to fill your canner at one time. If you have an extra filled jar or two that won't fit in the canner, refrigerate that unprocessed jar and eat its contents within 3 days.
- Remove one sterilized jar from the simmering water. Pack food and liquid into the hot jar using a jar funnel. Jar funnels often come in canning utensil sets like this Ball canning set ($7.49, Target). Ladle boiling liquid over the food, leaving adequate headspace.
- Allow the exact amount of headspace recommended by the recipe. Use a ruler to measure.
- Release trapped air bubbles by gently working a sterilized nonmetal utensil (such ones provided in a canning kit) down the jar sides. If headspace changes as bubbles are released, add more hot food or liquid to maintain headspace. Headspace allows food to expand when heated and the vacuum seal to form.
- Wipe rims of filled jars with a clean, damp cloth (food left on the rims prevents a perfect seal). Place lids on jars; screw on bands.
- As each jar is filled and assembled, use a jar lifter to place it gently in the canner.
- Be sure that jars do not touch each other, and each time you add a jar, put the canner lid back on.
- When all jars have been added, measure to make sure they are covered by 1 inch of water. If any jar tops are poking out, add some of the extra simmering water ready in your teakettle or other pot.
- Cover the canner and heat the water to a full rolling boil. Begin timing, following your recipe exactly. This is what's called the processing time. Boiling water bath canning times vary depending on many factors of each individual canning recipe. Stick to the recipe and you'll be fine.
- Check your water occasionally while processing canning jars, and adjust your burner as necessary to keep water at a steady, gentle boil. If water is boiling so hard that the jars are clinking together, turn it down. If the water has stopped boiling, turn the burner up and stop timing until water returns to boiling.
- At the end of processing, use the jar lifter to pull jars from the canner and transfer them to a wire rack or onto towels to cool. Space the jars about an inch apart so air can circulate around them. Let the jars cool 4 to 5 hours.
- Once the jars are completely cooled, test the seals by pressing the center of each lid. If the dip in the lid holds, the jar is sealed. If the lid bounces up and down, the jar isn't sealed. Check unsealed jars for flaws, the contents of unsealed jars can be refrigerated and used within 2 to 3 days, frozen, or reprocessed within 24 hours.
- To reprocess, use a clean, sterilized jar and a new lid; process for the full length of time specified in your recipe. Mark the label so you can use any recanned jars first. If jars have lost liquid but are still sealed, the contents are safe, but any food not covered by liquid will discolor (so use these jars first).
- After processing, wipe the jars and lids. Remove, wash, and dry the screw bands, and store them for future use. Label your jars with their contents and the date they were processed. Include a batch number if you can more than one batch in a day (if a jar spoils, you can identify others from the same batch). Store jars in a cool (50 to 70°F), dry, dark place. Use within 1 year.
With these water bath canning basics as your guide, and a trusted canning recipe, you'll be savoring all your favorite produce year-round, even if it's not in season.