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Water-Bath Canning

The safe, beginner-friendly method for high-acid foods: jams, jellies, pickles, fruit, and acidified tomatoes. All you need is a tall stockpot, a rack, jars, and a tested recipe.

How it works

High-acid foods (pH below 4.6) can be safely preserved in a boiling-water bath because acid and 100 °C heat together kill the bacteria, yeasts, and moulds that spoil food. Low-acid foods cannot — those need a pressure canner.

When to use this method

Good candidates: jams, jellies, fruit butters, fruit packed in syrup, pickles (with 5 % vinegar), salsa (tested recipe), and tomatoes acidified with bottled lemon juice or citric acid.

Authority sources

How water-bath canning preserves food

Three things have to happen at once for a jar of preserved food to be shelf-stable: heat kills the microbes already on the food, the recipe's acidity stops new microbes from growing, and a vacuum seal forms as the jar cools so no new microbes can get in.

The boiling water bath supplies the heat — 100 °C is the highest temperature water reaches at sea level, and that's enough for high-acid foods. The acid (the recipe's own pH, or added bottled lemon juice or vinegar) handles the rest. The seal happens during cooling: hot air and steam contract, the SNAP lid's sealing compound bonds to the rim, and atmospheric pressure pushes the lid down. A properly sealed jar of high-acid food keeps for a year or more on a pantry shelf.

What water-bath canning cannot do is destroy Clostridium botulinum spores. Those need 116 °C (the temperature only a pressure canner reaches) and they're the reason low-acid foods — vegetables, meats, beans, soups — must be pressure canned. See the pressure canning pillar for that side of the work.

The pH 4.6 rule — the single most important fact in water-bath canning

C. botulinum cannot grow in food with a pH below 4.6. That number is the boundary between "safe to water-bath can" and "must be pressure canned." It is the number Bernardin's recipes are built around. Memorize it.

  • Naturally high-acid (at or below pH 4.6): most fruit, jam, jelly, vinegar pickles, fermented pickles, fruit butter.
  • Borderline — needs added acid: tomatoes. Modern tomato varieties sit right on the line, and a single low-acid tomato can push the jar above 4.6. We publish no pH range for tomatoes or for any other food: the 4.6 threshold is published and a per-food value is not, and which side of the line a food falls on is what changes what you do. Every tested Canadian tomato recipe specifies bottled lemon juice or citric acid — 1 tbsp lemon juice per 500 mL, 2 tbsp per 1 L. Bottled, because fresh lemon acidity varies. The full acidity rule and why spaghetti sauce is not safe for water-bath without the right recipe.
  • Low-acid (pH above 4.6) — never water-bath can: all vegetables (green beans, corn, carrots, peas, potatoes), all meats, poultry, fish, beans, mushrooms, plain pumpkin or squash, dairy. These foods must be pressure canned — and a pressure cooker is not the substitute for a canner you do not own. Bernardin's only approved methods are a boiling water canner and a pressure canner, so there is no tested processing time to apply to any other appliance. The methods Bernardin says not to use.

The acid does not kill the spores — nothing in a boiling-water canner does, which is what the section above says. It stops them growing, and that is the whole barrier: below pH 4.6 the surviving spores cannot germinate or produce toxin. Without it, water-bath canning of a low-acid food is how home-canned green beans put people in the hospital. There is no shortcut and no edition of Grandma's recipe that overrides this.

Equipment you need

Water-bath canning has the lowest equipment bar of any preserving method. Most kitchens already have most of it.

  • A boiling water bath canner — a tall stockpot with a fitted rack to keep jars off the bottom. A 21–22 litre Bernardin or Granite Ware canner takes seven 1 L jars in one batch (Bernardin's Complete Book of Home Preserving, p.7). A regular tall stockpot works if you can fit a rack and have at least 2.5 cm (1 inch) of water above the jar tops during the boil. Our water-bath canner buying guide compares the models worth buying in Canada.
  • Bernardin jars — 125 mL, 250 mL, 500 mL, or 1 L depending on the recipe. Jars are reusable for years, as long as HealthLink BC's standard holds — rims perfectly smooth, no scratches or cracks. Check every rim by fingertip before each use.
  • SNAP lids — flat metal discs with red sealing compound. Single-use only — see why SNAP lids cannot be reused.
  • Bands — the metal screw rings. Reusable for years if they're not bent or rusted.
  • Jar lifter — rubber-coated tongs sized for mason jars. Dropping a hot jar into boiling water is a serious burn risk; do not improvise with regular tongs.
  • Lid magnet (optional) — a small wand for lifting SNAP lids without touching the sealing compound. Bernardin advises against preheating the lids at all: the sealing compound performs better at room temperature.
  • Headspace tool — a notched plastic stick that measures jar fill levels. Doubles as a debubbler to release trapped air after packing.
  • Wide-mouth funnel — keeps the jar rim clean while ladling. A seal forms against the rim, so anything left on it is in the way.
  • Bottled lemon juice or citric acid — for any tomato recipe. Bottled, not fresh; the acidity of fresh lemons varies too much to be reliably safe.

Shopping for gear? Our Canadian canning equipment guides compare every canner, jar, and tool worth buying — in Bernardin metric sizes and Canadian prices.

What foods can you water-bath can?

Anything that's naturally below pH 4.6, plus tomatoes when properly acidified. The Canadian gateway recipes — the ones to start with — are listed first:

  • Strawberry jam — the entry-point recipe most Canadian canners learn first. See the Bernardin-tested method.
  • Dill pickles — cucumber + vinegar + dill + salt. Full method here.
  • Applesauce — fall staple. Our method.
  • Crushed or whole tomatoes — September's biggest project, with the acidification rule above. The Bernardin method.
  • Jelly — apple, crabapple, grape, mint, hot pepper.
  • Salsa — must use a tested recipe (the ratio of tomato to onion/pepper matters for pH). Tested Canadian salsa.
  • Fruit in syrup — peaches, pears, plums, cherries.
  • Fruit butters and curds — apple butter, pear butter.
  • Chutneys, relishes, condiments — corn relish, bread-and-butter pickles, pickled beets.

Corrected 19 September 2026: this page used to send you to a recipe book published by Health Canada, and in step 2 below to a recipe they had tested. Neither exists — Health Canada publishes no recipes and no catalogue of them. What Health Canada publishes is the rule — use only current, tested home canning recipes — and Bernardin publishes the recipes. If you went looking for a Health Canada recipe and came back with nothing, that is why. Nothing you canned to a Bernardin recipe is affected.

Not on this list and not in your Bernardin edition? Assume it's pressure-canning territory until you've checked. Bernardin's Complete Book of Home Preserving (ISBN 978-0-7788-0137-5) is the edition this site works from; Health Canada publishes the rule to use a tested recipe, not the recipes themselves.

The water-bath process in 8 steps

  1. Heat the canner. Fill with enough water to cover the jars by 2.5 cm. Bring to a simmer while you prep.
  2. Inspect and warm the jars. Check every rim for chips (your finger will catch a flaw the eye won't). Place clean jars in simmering water to keep them hot until filled.
  3. Prep the food. Health Canada's rule is to use only current, tested home canning recipes; Bernardin is the Canadian source that publishes them. Follow a tested Bernardin recipe — exact ingredient quantities, acid additions, and cooking method.
  4. Fill the jars. Use a funnel. Leave the headspace the recipe specifies — typically 0.5 cm for jams and jellies and 1 cm for pickles, tomatoes and fruit in syrup. Too little headspace causes siphoning; too much prevents a vacuum seal.
  5. Debubble and wipe. Run the headspace tool around the inside to release trapped air. Wipe the rim with a clean damp cloth — any sticky residue kills the seal.
  6. Apply lids fingertip-tight. Centre a fresh SNAP lid; screw the band on until you feel resistance, then a quarter-turn more. Do not over-tighten — air needs to escape during processing.
  7. Process. Lower jars into the canner with the jar lifter. Cover with a lid. Start timing when the water returns to a full rolling boil. Add minutes for your altitude band.
  8. Cool and check seals. Turn off heat, wait 5 minutes, lift jars onto a towel-lined counter. Leave undisturbed 24 hours — pressing or tapping a lid while the vacuum is still forming can interrupt the seal. Some lids ping as they seal and some stay silent; the sound proves nothing in either direction. Press the centre: a lid that flexes or clicks has not sealed. One that stays firm and concave has no defect you can feel, which is not the same as a guarantee.

How long does water-bath canned food last?

Bernardin recommends consuming home-canned food within one year for best quality. That is a quality window rather than an expiry, and the conditions Bernardin attaches are not calendar ones: “If the jar of food was processed according to current home canning recommendations, and the jar is still vacuum sealed, the food should be safe to eat.” What the year governs is flavour, colour and texture, which keep degrading the longer a jar sits.

Storage rules that actually matter:

  • Cool, dark, dry. Pantry, basement shelf, or cupboard — not above the stove, not in direct sunlight, not in a freezing unheated garage (freeze-thaw cycles can break seals).
  • Remove the bands after the seal sets. Bands trap moisture against the lid edge and can mask a failed seal. The lid holds itself once sealed.
  • Label every jar with the date. Six months in, you will not remember which batch was July and which was September.
  • Inspect before opening. Bulging lid, off smell, mould, discolouration, or a hissing release of pressure all mean discard. The full discard checklist.

See our full shelf-life guide, which sets the one-year figure out category by category and explains why Bernardin publishes one figure for home-canned food rather than a different one per food.

Common failures (and how to avoid them)

  • Jar didn't seal. Most common cause: reused SNAP lid, dirty rim, or wrong headspace. The 24-hour reprocess rule covers what to do.
  • Not sure it sealed — the lid never "popped." The pop isn't proof of a seal, and a quiet lid can still be sealed. Press the centre: a lid that flexes or clicks has not sealed. Staying firm finds no defect; it does not clear the jar. How to actually tell if a jar sealed.
  • Jam didn't set. Usually low pectin, low acid, or undercooking. The cold-plate test tells you in 60 seconds.
  • Siphoning (food residue stuck to the lid after processing). Caused by yanking the canner lid mid-cool, processing in too-cold water, or wrong headspace. Cool the canner gradually.
  • Jar cracked or broke in the canner. Usually thermal shock — cold jars lowered into boiling water — or a rim chip you missed. Why chipped and cracked jars can't be safely canned.
  • Cloudy brine in pickles. Sometimes harmless (calcium in your water), sometimes bacterial activity. If accompanied by an off smell or visible mould, discard the jar.
  • Pickles turned soft or mushy. Bloom-end enzymes, no added calcium, a weak brine, or over-processing. The five reasons pickles go soft — and how to keep them crisp.
  • Failed acidification on tomatoes. Skipping the bottled lemon juice or citric acid is the most dangerous shortcut in water-bath canning — modern tomato varieties sit right on the pH 4.6 line. Read the pH rule before improvising any tomato recipe with onions, meat, oil, or other low-acid ingredients.

Altitude matters

The processing time printed in a recipe applies up to 305 m — Bernardin's base band, not sea level. Above that, you add minutes — the exact addition is published by Bernardin.

Bernardin publishes one boiling-water table and it covers every recipe. Up to 305 m — Halifax, Toronto, Montréal, Vancouver, Winnipeg — you add nothing. From 306 to 915 m you add 5 minutes: Kelowna, Saskatoon, Regina, Edmonton, Whitehorse. From 916 to 1,830 m you add 10 minutes: Calgary, Lethbridge, and the mountain towns. The two bands above that (+15 and +20 minutes) start at 1,831 m, higher than anywhere in Canada people live. Our altitude-adjustments guide lists every Canadian city and its adjustment.

When to switch to pressure canning

Water-bath is the right answer for high-acid foods only. If you're looking at any of the following, you're in pressure-canning territory and water-bath is not safe:

  • Plain vegetables (green beans, corn, carrots, peas, beets without vinegar) — see why they can't be water-bath canned
  • Any meat, poultry, fish, or shellfish
  • Dried beans or any soup with beans, meat, or vegetables
  • Stocks, broths, gravies
  • Plain pumpkin or winter squash (cubed or strained — pumpkin butter is also unsafe)
  • Mushrooms
  • Dairy or any recipe with milk, cream, or butter
  • Pasta, rice, or other thickeners that block heat penetration

The dividing line is pH 4.6, and adding "lots of vinegar" or "lots of lemon juice" to a low-acid recipe does not make it water-bath safe — only a tested recipe with measured acidification (like our dill pickles, pickled jalapeños, or canned salsa) clears the bar. See the pressure canning pillar for the method that handles everything else.

Every guide in this method

See the articles index for the full archive.

Sources