Steam canning: what changed, and when
Sources last opened 2026-08-26.
The short version
Atmospheric steam canning is research-tested for acid foods, and has been since 2015. If you are reading somewhere that it is unsafe, that page is probably quoting the USDA guide, which is a real, current document that really does say so — and which the research centre that maintains it publicly moved past in the same year it was published.
Both texts are live today. Neither is a hoax and neither is out of date in the sense of having been withdrawn. What follows is all three of them, with dates, and then the conditions that actually apply if you use one.
Two organisations, one of which maintains the other's document
The USDA Complete Guide to Home Canning is a fixed document. The 2015 revision is the current one, it has not been superseded, and it says steam canners are not recommended.
The National Center for Home Food Preservation, at the University of Georgia, maintains that guide. It is a live website, and it says atmospheric steam canning is research-tested for acid foods.
Those two things are both true right now. Nobody is lying and nothing has been withdrawn. A fixed document was published, the research it was waiting on finished, and the live site moved before the fixed document could be revised — which the live site says explicitly.
Almost every argument you will find online about whether steam canners are safe is two people each holding one of these texts.
The seven conditions, in full
This is the part that gets dropped. Pages that say "steam canning is approved now" usually stop there, and the approval is conditional on all seven of these:
- The food is naturally acid or properly acidified, at a pH of 4.6 or below [F-6.2].
- The air is vented out of the steam before processing begins [F-6.2].
- The steam is pure and at the temperature of boiling water at the start and throughout — that is 212°F at sea level [F-6.3].
- The jars are preheated before filling, and cooling before processing is kept to a minimum [F-6.2].
- The process time is adjusted for altitude and comes to 45 minutes or less including that adjustment [F-6.2].
- The canner is never opened during the process, for any reason, including to add water [F-6.2].
- The jars cool in still, ambient air, with no forced or accelerated cooling [F-6.2].
Wisconsin Extension, whose food scientist led the research, adds the operating detail that tells you it is working: a 6- to 8-inch column of steam should be venting from the holes in the side of the canner for the entire timed process [F-6.3]. It also notes that the approved recipes cover half-pint, pint and quart jars [F-6.3].
Condition five is the one that changes your plans. Run the altitude adjustment first, and if the total lands over the 45-minute ceiling [F-6.2], the recipe is not a steam-canner recipe. Use a boiling water canner instead, where there is no such ceiling.
What it does not change
A steam canner is not a pressure canner and does not become one. It reaches the temperature of boiling water and stops there, which is the same ceiling a boiling water canner has [F-1.2]. Every food that needs a pressure canner still needs one.
If it helps to hold one idea: the water bath and the steam canner are the same tool with different plumbing. What separates them from a pressure canner is not the vessel, it is the temperature, and temperature is the only thing that kills Clostridium botulinum spores [F-1.8].
Where this leaves a page you find tomorrow
Three questions, and they work on any canning page, not just this subject.
Which document is it quoting? "The USDA says" is not a citation. The 2015 guide and the live NCHFP site are different texts that disagree in at least three places, and a page that treats them as one thing has not read either carefully. The other places they come apart — including one safety panel that exists in two non-identical versions [F-14.6] — are laid out in which document is current, and how to tell.
What is the date on the claim? A 2023 land-grant Extension page lists steam canning among the methods it currently recommends [F-6.5]. A 2015 federal document lists it among the ones it does not [F-6.1]. Both are current. Neither is wrong about what it says.
Do the title and the body agree? At least one heavily-ranking page fails this test on this exact subject [F-6.6]. Titles are written for search results; bodies are written after somebody has read the research. When they disagree, believe the body, and be careful what you pass on from a search result you did not open.
Text one, and it is still in print
Steam canners are not currently recommended because processing times for use with current models are still being researched.
USDA Complete Guide to Home Canning, 2015 revision, p. 1-10
The link above opens the document itself, so a printed page number leads somewhere. What this document is, and who maintains it.
Opened and read by this site on 2026-08-26.
This is the current revision of the USDA guide. Not a superseded edition, not a draft — the 2015 revision is the one in circulation right now, and this sentence is in it.
Note the reason it gives. It does not say steam canners were tested and failed. It says the research had not finished. That is a claim about the state of knowledge in 2015, and the state of knowledge changed.
Text two, from the people who maintain text one, published the same year
Sufficient studies and peer review have been completed that we are now able to say that as long as certain critical controls at various steps in the canning process are achieved, USDA and NCHFP process times for canning acid or properly acidified foods (pH of 4.6 or below) at home with properly research based recipes and procedures can be used.
NCHFP, Burning Issue: Using Atmospheric Steam Canners, May 2015
Opened and read by this site on 2026-08-26.
The National Center for Home Food Preservation is the body that maintains the USDA guide. This is that body saying the research finished and the answer came back yes, under stated conditions.
The research is a named, peer-reviewed paper — Willmore, Etzel, Andress and Ingham, Food Protection Trends, May–June 2015 — not an opinion post. Read the conditions below before you take this as a green light, because there are seven of them and one of them rules out a lot of recipes.
Text three, and this is the one that tells you everything
It will take some time to integrate advice into the USDA "Complete Guide to Home Canning" or other publications.
Opened and read by this site on 2026-08-26.
That sentence is on NCHFP's own page, in an "Update on Steam Canning" paragraph that sits directly beneath a verbatim reproduction of the 2015 line saying steam canners are not recommended. Both paragraphs, same page, one under the other.
This is worth being precise about, because it is easy to describe unfairly. NCHFP has not forgotten to update the page. It has updated the page, left the superseded sentence standing above the update, and told you in plain words that the primary document is behind its own research centre.
A maintainer saying that out loud is the most useful sentence on this whole site. It is why every page here prints which document it is quoting and when that document was written.
What people ask next
So is a steam canner safe or not?
For acid or properly acidified foods, with the conditions below met, it is research-tested. For anything low-acid — beans, corn, meat, plain vegetables — it is not, has never been, and no amount of time will make it so. A steam canner is an atmospheric vessel. It reaches the temperature of boiling water and no higher, exactly like a boiling water canner, so it sits on the same side of the line.
Why does the 45-minute limit exist?
Because the canner base holds a fixed amount of water and cannot be topped up mid-process — the canner is never opened during processing, for any reason. A long process risks running the base dry. That single condition rules out a good number of recipes, and it is the one most often left off pages that mention steam canning approvingly.
A page I found says steam canners are unsafe. Is it just old?
Sometimes. But check whether the page's title and body agree with each other before you decide. One widely-ranking page carries "Steam Canners" in a title listing unsafe methods while its body calls atmospheric steam canning research-tested. A reader who only sees the search result learns the opposite of what the page says.
Read these yourself
NCHFP — Burning Issue: Using Atmospheric Steam Canners
nchfp.uga.edu
NCHFP — Equipment and Methods Not Recommended
nchfp.uga.edu
University of Wisconsin–Madison Extension — Preserving acid foods with a steam canner
fonddulac.extension.wisc.edu
SDSU Extension — The 'why' behind unsafe canning practices
extension.sdstate.edu