Can You Sterilize Canning Jars In The Dishwasher? | Not Safe

You load the dishwasher, click “sanitize,” and imagine it kills every germ in your mason jars. It’s a convenient image, and plenty of home canners have tried it. The dishwasher feels like a logical shortcut — after all, it gets hot, and it’s designed to clean. Why wouldn’t it sterilize?

The problem is temperature and time. Dishwasher sanitize cycles typically max out around 150–160°F, while true sterilization requires sustained heat at 212°F for 10 minutes. The University of California Cooperative Extension and the National Center for Home Food Preservation (NCHFP) are clear: dishwashers are for cleaning, not sterilizing. Here’s why that distinction matters and what you should do instead.

Why Dishwashers Fall Short

Sterilization means destroying all microorganisms, including bacterial spores like those that cause botulism. To do that, moist heat at 212°F (100°C) must be maintained for a full 10 minutes at sea level. A dishwasher’s sanitize cycle simply doesn’t deliver that.

Most residential dishwashers reach about 150°F for only a few minutes. That temperature can kill some bacteria, but it won’t reliably kill heat-resistant spores. The NCHFP points to a boiling-water canner as the only home method that provides the consistent moist heat needed.

Altitude also plays a role. At 1,000 feet above sea level, you need to boil jars for 11 minutes instead of 10, adding one minute per additional 1,000 feet. A dishwasher cannot adjust for altitude.

Cleaning vs. Sterilization: Why the Distinction Matters

It’s easy to think the dishwasher’s “sanitize” cycle does the same job as a boiling-water canner. But the two processes serve different purposes. Cleaning removes food residue and reduces the number of microorganisms. Sterilization eliminates virtually all microorganisms, including spores. Confusing the two can lead to unsafe canned goods.

• Dishwasher is fine for cleaning: Hot water and detergent remove grease and debris from jars before canning. Michigan State University Extension recommends washing jars in the dishwasher but clarifies this is not sterilization.
• Dishwasher cannot kill spores: The temperature is too low and too brief to destroy Clostridium botulinum spores. The UC Cooperative Extension explicitly calls dishwasher sterilization “a no.”
• Sterilization is only needed for short-process foods: If your recipe will be processed in a boiling-water canner for 10 minutes or more, the processing itself sterilizes the jars. No separate step is required.
• For foods processed less than 10 minutes: Jars must be sterilized beforehand using the boiling-water canner method. This includes many jams, jellies, and pickles with short processing times.

The bottom line: treat the dishwasher as a tool for cleaning and keeping jars hot — not as a substitute for proper sterilization. When in doubt, check the processing time of your recipe against the 10-minute rule.

When Sterilization Is Actually Required

Understanding when to sterilize saves time and keeps your pantry safe. The NCHFP’s rule is simple: if your food will be processed in a boiling-water canner for 10 minutes or more, you only need clean, hot jars. If the processing time is less than 10 minutes, you must sterilize the jars first.

The USDA and NCHFP provide specific guidance for jar sterilization — see their sterilize empty jars page for the full details. The method: place jars upright on the canner rack, fill the canner with hot water to 1 inch above the jar tops, bring to a rolling boil, and boil for 10 minutes (at altitudes below 1,000 ft). Keep them in the hot water until you’re ready to fill them.

Some canners ask about oven or microwave sterilization. The USDA does not recommend either method. Dry heat is less effective at penetrating and killing spores, and microwave heating is uneven and unreliable. The boiling-water canner remains the only USDA-approved method for home jar sterilization.

Stick with the method that extension services trust. A little boiling water beats a ruined batch of jam — or worse, a food safety risk that could land someone in the hospital.

How to Keep Jars Hot Without Sterilizing

Even when you don’t need to sterilize, you still need to keep jars hot before filling them. Pouring hot food into a cold jar can cause thermal shock, cracking the glass. The dishwasher can help here — but only to hold heat, not to sanitize.

1. Use the dishwasher’s keep-warm cycle: After the wash cycle ends, leave the jars inside with the door closed until you’re ready. This maintains warmth without overcooking the jars.
2. Place jars in the canner as it preheats: Set clean jars in your empty canner, fill with water, and bring it up to temperature. The jars heat along with the water.
3. Create a separate hot-water bath: If your canner is busy, fill a large pot with hot water, submerge the jars, and hold them at 180°F until needed. This is also useful for keeping lids warm.
4. Avoid rapid temperature changes: Never put a hot jar on a cold counter or add cold liquid to a hot jar. Gradual temperature shifts prevent cracks.

Michigan State University Extension endorses these approaches. The key is to treat the dishwasher as a holding oven for clean jars, not a sterilization device.

The Right Way to Sterilize Jars

When your recipe requires sterilized jars — for jams, jellies, or pickles processed less than 10 minutes — follow the USDA’s boiling-water canner method. It’s simple and reliable.

Start by washing jars in hot soapy water or the dishwasher. Rinse well. Then place them upright on the canner rack, fill the canner with enough hot water to cover the jars by at least 1 inch, and bring to a rolling boil. Start the timer once the water is at a full boil, and boil for 10 minutes (at altitudes below 1,000 ft).

The University of California Cooperative Extension explicitly states in its dishwasher sterilization no document that dishwasher sanitize cycles are insufficient. The heat simply isn’t high enough or held long enough. For altitudes above 1,000 ft, add 1 minute of boiling time for each additional 1,000 ft. Keep the jars in the hot water until you’re ready to fill them.

The Bottom Line

Dishwashers cannot replace a boiling-water canner for jar sterilization. They fall short on both temperature and duration. The dishwasher is fine for cleaning and keeping jars hot, but the only home method the USDA and university extensions endorse for sterilization is the 10-minute boil (adjusted for altitude).

If you’re unsure whether your recipe requires sterilized jars, check the processing time — if it’s less than 10 minutes, take the extra step. For personalized advice on canning safety, your county extension office or a certified Master Food Preserver can answer questions specific to your altitude and equipment.