Pressure canner vs water bath canner

High acid versus low acid foods

Canning safety starts with acidity. USDA and NCHFP draw the line at pH 4.6. Foods at pH 4.6 or below are high acid. Foods above pH 4.6 are low acid.

High acid foods include most fruits, jams and jellies, fruit juices, pickles and relishes made with tested vinegar recipes, and tomatoes with added lemon juice or citric acid as the tested recipe directs. Low acid foods include all fresh vegetables (other than properly pickled ones), meat, poultry, seafood, beans, soups and stocks, and mixtures that contain any of these. Our what foods need pressure canning page lists common examples.

Temperatures each method reaches

In a water bath canner, jars sit on a rack under boiling water. Water cannot get hotter than its boiling point at normal pressure, which is about 212 F at sea level and lower at altitude. That is enough to kill molds, yeasts and most bacteria in high acid food, and the acid itself keeps botulism spores from growing.

A pressure canner locks the lid and builds steam pressure. At 10 psi on a weighted gauge at sea level, the inside reaches about 240 F. The spores of Clostridium botulinum survive boiling water but are destroyed at 240 F when held for the tested processing time. In a sealed jar of low acid food, any surviving spores can grow and produce a deadly toxin without obvious signs of spoilage. That is why USDA states that pressure canning is the only safe method for low acid foods.

Note.Never water bath can vegetables, meat, poultry, seafood or beans, and never shorten a tested process. Use current USDA or NCHFP tested recipes, and follow the canner maker's instructions for venting and water depth.

Pressure canners in our catalog

All three pressure canners below can also be used as a water bath canner for high acid foods, which is why many people buy one pressure canner rather than two pots. The two Presto listings say so directly. For the All American, use it with the lid resting loosely and no pressure, or keep a separate stockpot; check the maker's manual.

See the best pressure canners →

Water bath canners and electric options

A water bath canner is simply a deep pot with a rack and lid, tall enough to cover jars with at least 1 inch of boiling water. Electric water bath canners such as the Ball freshTECH and Ball EasyCanner sit on the counter and hold the water at temperature for you. Both Ball listings state a 21 quart capacity holding 7 quart jars or 8 pint jars.

These are for high acid foods only. They do not build pressure and cannot reach 240 F, so they are never a substitute for a pressure canner with low acid foods. For a countertop pressure canner, see our electric vs stovetop pressure canner comparison.

How altitude changes each method

Water boils at a lower temperature as you go up, so both methods need adjusting. For water bath canning, tested recipes add processing time at higher altitudes. For pressure canning, the time stays the same but the pressure goes up. USDA lists weighted gauges at 10 psi up to 1,000 ft and 15 psi above, and dial gauges stepping from 11 psi up to 15 psi in 2,000 ft bands to 10,000 ft. Use our pressure by altitude tool or the pressure canner altitude chart, and always confirm against the recipe's own table.

Which canner to buy first

Before your first batch, read how to use a pressure canner and how much water goes in a pressure canner. If you own a dial gauge model, plan on testing the gauge each season.

• Only jams, jellies, fruit and pickles: a water bath canner is enough.
• Vegetables, beans, stock, meat or soups: you need a pressure canner.
• Both: buy a pressure canner that doubles as a water bath canner, such as the Presto 01781 or 01784.
• Glass top or induction cooktop: check compatibility first; see best pressure canners for glass top stoves.

Frequently asked questions

Can I use a pressure canner as a water bath canner? Many models can, including both Presto canners above according to their listings. Leave the vent open or the weight off so no pressure builds, and cover jars with water as for a normal water bath.

Can I water bath can tomatoes? Yes, if you add lemon juice or citric acid exactly as a tested USDA or NCHFP recipe directs. Without added acid, tomatoes can sit too close to the pH 4.6 line.

Is a pressure cooker the same as a pressure canner? No. Many small cookers are not designed or tested for canning. See pressure canner vs pressure cooker.

How long do home canned foods keep? NCHFP advises using them within about 1 year for best quality, stored cool, dark and dry. See how long home canned foods last.