Some foods are safe to can in boiling water. Others aren’t. The right method depends on the acidity of what you’re preserving. High-acid foods can be canned using a basic water bath. Low-acid vegetables, meats, and stocks require pressure canning to reach a higher temperature and kill bacteria that boiling can’t touch. This handy guide explains how both methods work and which one you’ll need for different foods on your shelf. Water Bath Canning: Best for High-Acid Foods Water bath canning uses boiling water to seal jars of high-acid foods. The heat forces out air, creates a vacuum, and stops bacteria from growing. This method requires a deep pot with a rack and a tight-fitting lid. Use water bath canning only for foods that have enough acidity to prevent spoilage. Recommended foods: Jams, jellies, and fruit preserves Pickles and vinegar-based relishes Applesauce, peaches, pears, and other fruits Tomatoes (with added acid such as lemon juice or vinegar) Fruit chutneys and syrups Boiling water should cover the tops of the jars by at least one inch. Start the timer once the water reaches a rolling boil and follow the full processing time for the recipe. The National Center for Home Food Preservation offers tested recipes and safe acidity guidelines for water bath canning. Pressure Canning: Required for Low-Acid Foods Pressure canning uses steam under pressure to raise the internal temperature of the canner to 240°F or higher. This level of heat is necessary to kill harmful bacteria, including the spores that cause botulism. Use pressure canning for any low-acid food. Recommended foods: Green beans, corn, carrots, and other plain vegetables Potatoes, mushrooms, and winter squash Dry beans (after soaking or precooking) Meat, poultry, and fish Bone broth, soup stock, and chili Only use a pressure canner designed for home food preservation. It should have a locking lid, pressure regulator, and either a weighted or dial gauge. Water Bath vs Pressure Canning: Key Differences Feature Water Bath Canning Pressure Canning Heat Level 212°F (boiling) 240°F+ (pressurized steam) Best For High-acid fruits and pickled foods Low-acid vegetables, meats, and stocks Required Equipment Deep pot with rack and lid Pressure canner with gauge or weight Shelf Life 12–18 months 12–18 months Time Range 10–30 minutes 20–90 minutes Spoilage Risk Low (if acid is sufficient) High if pressure is not used properly Why Acidity Changes the Method Acid levels determine whether boiling is enough to keep food shelf-stable. High-acid foods (pH below 4.6) resist bacterial growth on their own. These can be safely canned in boiling water. Low-acid foods don’t provide that protection. Without higher temperatures, bacteria, including botulism spores, can survive and grow inside sealed jars. In summary, your canned produce’s smell, taste, and appearance do not confirm safety. To ensure safety, choose the right canning method based on your food’s acidity. How to Choose the Right Method Use water bath canning when preserving high-acid fruits or recipes made with vinegar. It’s simple and doesn’t require expensive equipment. Use pressure canning when working with vegetables, meats, or any low-acid food. This is the only safe option for shelf-stable canning in these cases. Many homesteaders use both methods throughout the year depending on what they’re preserving. What are you canning this season? Let us know what you’ve put up and which method you used, your experience might help another homesteader plan their pantry. FAQ: Water Bath vs Pressure Canning Can I use lemon juice or vinegar to water bath can low-acid vegetables? No. Unless the recipe has been tested for safety, adding acid doesn’t guarantee protection. Use pressure canning. Do I need to sterilize jars before pressure canning? No. The high heat during pressure canning sterilizes jars. Just wash them with hot, soapy water first. Can I use a pressure cooker instead of a pressure canner? No. Most pressure cookers are not tested or rated for safe food preservation. Use a certified pressure canner. Which foods must be pressure canned? Plain vegetables, meats, fish, and broth always require pressure canning, even if mixed with other ingredients. How do I check if a jar is sealed correctly? Once cool, press the lid center. It should not flex. A sealed lid stays firm and slightly concave.