Water Bath vs. Pressure Canning: Which Foods Need Which

This is the first question every home canner has to answer, and the rule is friendlier than it looks. You don't need to memorize a chart of foods. You need to know one line, and to follow a tested recipe on the right side of it.

What's the short answer?

Altitude changes both. For water bath, the time changes. For a stovetop pressure canner, the pressure changes. See canning at altitude.

Some foods sit in between:

• Tomatoes and figs: water bath only when acid is added as a tested recipe says. The USDA says some are slightly above pH 4.6.
• Pickled vegetables: water bath only with a tested pickling recipe. The recipe adds the acid. A plain vegetable is low-acid.
• Mixes of low-acid and high-acid foods: go by the tested recipe. Without enough added acid they count as low-acid. The USDA says most such mixes are above 4.6 unless the recipe has enough lemon juice, citric acid or vinegar.

We publish no times, pressures or recipes, on purpose. Your tested recipe gives those. Where to find tested recipes has the sources. Our low-acid foods list goes further into which foods fall where.

Why isn't boiling enough?

The worry is Clostridium botulinum, the germ behind botulism. The USDA says its spores are very hard to kill at boiling-water temperatures. The hotter the canner, the easier they die. High-acid foods have enough acid to block the germ or kill it faster when heated. Low-acid foods don't.

Water in an open pot stops getting hotter once it boils. A pressure canner traps steam, and that lets it get hotter. The USDA is careful here: pressure itself doesn't kill germs. High heat held long enough does. The CDC says a boiling water canner does not protect against botulism in low-acid foods, so boiling longer is no way around it. The botulism page has more.

Have no pressure canner and a basket of green beans? Our page on canning without a pressure canner has honest alternatives.

How do the two methods compare?

• What you can can. A pressure canner is the wider tool. It's required for low-acid food, and some pots double as water bath canners when used without pressure. A water bath canner handles high-acid foods only.
• Speed. The USDA recommends boiling water canners for high-acid foods because they're faster. A pressure canner adds venting, building pressure and cool-down.
• Attention. A water bath needs jars covered with water and a steady boil. A stovetop pressure canner needs venting, careful watching of pressure, and a cool-down you can't rush. The USDA warns that force-cooling the canner may result in unsafe food.
• Learning curve. Water bath is the usual place to start. A pressure canner has more steps, and your manual walks you through them. How to use a pressure canner gives the overview.
• Choosing a process. The National Center for Home Food Preservation (the US canning experts at the University of Georgia) says the right process depends on the food's acidity, the canner type, how it's packed, the jar size and your altitude. That's why one number can't travel from recipe to recipe.

Which machine does which?

Machines sold for canning aren't all the same type, so be sure which one you have.

• Stovetop pressure canner: both methods on many models. Presto says the 01781 holds quart jars in both.
• Plug-in canner made just for canning: the Presto Precise is sold for both, with limits by size on our electric canner sizes page. The USDA and the National Center approve no canner of any kind. Nobody outside the company has published test results for it.
• Electric water bath: the Ball EasyCanner. It has no pressure setting.
• Electric multi-cooker: not a pressure canner. See canning in an Instant Pot.

Which machine does what sorts all five types.

Pressure canner or water bath: which one for you?

Which one, then?

• If you want to can vegetables, meat, poultry or seafood → Presto 23-Quart Stovetop (01781)

  View*(paid link to Amazon, opens in a new tab)Ad · paid link · check price & delivery on Amazon

• If you want a stovetop pot that can do both methods → Presto 23-Quart Stovetop (01781)

  View*(paid link to Amazon, opens in a new tab)Ad · paid link · check price & delivery on Amazon

• If you only make jams, fruit and pickles, and want the pot off the stove → Ball EasyCanner

  View*(paid link to Amazon, opens in a new tab)Ad · paid link · check price & delivery on Amazon

• If you only make jams, fruit and pickles and already own a tall pot

  Read about water bath first

• If you would rather plug in for both methods

  Electric vs. stovetop

For most readers who want a shelf of garden vegetables, a stovetop pressure canner is where we'd begin, since it handles both sides of the line. If you'll only ever can jam, a water bath is simpler. Either way, start small, with one tested recipe and a manual beside you.