Water Bath Canning 101

Note: This is the first kind of canning you should try, and the most basic, and IMHO, most useful kind. It is definitely worth experimenting with when you've got an excess of produce, which many people do this time of year. If you don't have your own overproductive garden, perhaps you can offer to preserve some for a friend with a garden, in exchange for some food - and most farmers offer bulk prices if you can buy in quantity. Try shopping at the end of the day, when farmers don't really want to take the food home anyway!

It is starting to be time to think about preserving food. Why think about it? Well, first of all, we waste almost half of all food in this country - much of it perfectly good food. Food preservation allows us to take everything we have and make it last into the season when it will be less abundant. Also, most healthy foods are cheapest when in season - preserving them now means that we have inexpensive, nutritious food available all winter long, rather than paying high out of season prices. There's also the fact that you can make sure you are getting healthy, safe food that tastes like you want it - nothing goes into it that you don't like, can't eat, or don't want your family exposed to. You can adjust it to your taste as well - make those pickles as spicy or mild as you like, cut the sugar from the jam. Food preservation is also a basic human work that ties us to our past and our history - for virtually all of human history, taking what is abundant and putting it aside for times of scarcity has been a central human project, and a deeply satisfying one.

Today's subject is Water Bath Canning, which is different than Pressure Canning. I'm going to start from the very beginning here - I know lots of people who read this blog already have a lot of experience on this front, but just in case you don't, it is worth going over the basics. The first thing I'm going to say is that I don't want you to be scared, and I don't want you not to try this, but I do want you to swear up and down before you do any canning that you will pay attention, read instructions carefully and follow the rules. Because, even though your Mom always did it this, you really can die from not being careful with canning. It probably won't happen - but why mess with it? Properly done, canning is easy and safe - just do it properly.

The National Center for Home Food Preservation is a great resource, with lots of up-to-date information and all sorts of recipes, do check out their website. I also recommend you purchase a post-1994 canning guide - many are available cheaply used, and the Ball Blue Book is quite inexpensive. It is important to have a hard copy because you most need instructions just when you are in the middle and can't remember the next step - arm deep in peaches is a bad time to run up and turn on the computer.

Water Bath Canning is the appropriate method for canning *only* high acid foods. Such foods include pickles, jams, jellies, fruit juices, rhubarb (which is technically a vegetable but so acidic it can be water bath canned) and all-tomato products (note that hyphen - I mean products that contain *only* tomatoes - not "all tomato products." Everything else must be pressure canned, with the exception of a few recipes formulated by professional food scientists that are safe to can by water bath canning - they come only from very recent and modern canning books and are ph tested both before and after canning to be safe. Don't make up your own.

The reason for this is that the bacteria, clostridium botulinum, that causes botulism, is endemic the soil - it is all over your vegetables and fruits in most cases. That's not a problem in an aerobic (there's plenty of air) environment - your body can handle it just fine (although babies under 1 year sometimes have trouble with it). But in a warm, anaerobic environment like a canning jar, it goes crazy. And botulism will kill you and your family - it is not something to mess with.

Now any food with a ph lower than 4.4 (acidic) provides an environment inhospitable to botulism - which is why high acid foods can be safely pressure canned. But, the thing is, most of us don't have the chemist's equipment to confirm acidity - for example, tomatoes can have an acidity level as low as 4.0, or as high as 4.7, if they are overripe or a low acid hybrid. And there are a couple of cases of botulism found in tomato products. Moreover, there are some molds that can slightly alter acidity, rendering a food that is marginal too low acid to be safely canned.

This is why following the instructions of a *RECENT* canning book is essential - any cookbook written before 1994 is not safe to use - that is, you can use the recipe, but you must follow current guidelines for canning - generally speaking, if you aren't using just fruit and sugar, or pickles, but mixing ingredients, say, in tomato sauce or salsa, you must follow the instructions for the ingredient in the food that requires the longest and most intense processing - that is, if you are making salsa with tomatoes and hot peppers, unless you know the recipe is safe (that is, you have gotten it from a USDA approved, recent book or website that specifically says that it is a combination food that is safe to water bath can, *AND* you have followed instructions exactly, not adding any more ingredients or changing proportions at all).

For tomato products with nothing else in them, add 2 tsp of lemon juice per pint, or 4 per quart, or the same amount of vinegar, to ensure their acidity stays below minimum levels. This might also be wise if you are canning very overripe fruit.

Ok, for canning you need a few things. You need a large pot with a lid - canning kettles with racks are great, but you can use any big pot with a lid, and something to keep the jars off the bottom of the pot so they won't break - a steamer, a baker's rack - anything that will lift the jars off the bottom and allow water to circulate. Ideally, you will also have a canning kit - it comes with a jar lifter (big tongs designed to lift full canning jars), a magnet (for pulling the lids out of boiling water), and a funnel the right size for pouring hot things into canning jars. You don't actually need these things - they are merely convenient - but they are really convenient, and nice and cheap, so I recommend them. You can take the jars out with regular tongs - I have done this. I've also had one splash back and send boiling water at me - your choice. You can fill the jars without the funnel, but why struggle? The stuff is also available used at your friendly neighborhood yard sale.

I have never bought a new canning jar - I get them constantly for a buck a box or sometimes $3 for 5 boxes - they are one of those things most people seem to have in their garage. Put out requests on freecycle or Craigslist, and see what you can find before you buy them.

The only ones that are really considered safe to use are the newer kind, that have two piece, screw on lids. The old ones with the jar rubbers can technically be used for high acid foods, but they aren't recommended, can only be used with new rubbers, and I'm not going to explain how to do it here, because there's a lot of controversy about whether it is safe. If you have the old zinc lid or wire and rubber canning jars, use them to display stored food, or store dehydrated stuff - don't can with them.

You don't need to buy new rings - as long as the rings aren't rusted through, and as long as they fit on the jar (often canning jars come with the rings), you can reuse them. These I occasionally do buy new, as not all jars come with them.

You need a new lid every time - and jars come in two sizes - regular and wide mouthed. So you not only need a new lid, but an appropriately sized one. I buy my canning lids buy the case, because I do a lot of canning - they store for quite some years as long as they are kept cool and dry, and are much cheaper if you can afford to buy them in bulk.

What about bisphenol-a? There is bisphenol-a on the lids of canning jars - however, if you are canning correctly, and don't tip the food around (which you shouldn't do anyway, because it can mess up your seal), your food should never come in contact with the lid. That's the magic of the correct headspace that allows you to create a vacuum seal. IMHO, home canned food is comparatively low risk this way, and that's another argument in favor of home canning, rather than buying commercially preserved food.

Now in a real crisis, it is technically possible, although NOT RECOMMENDED to reuse lids that have been carefully pried up and checked to ensure there are no dents or damage to the rubber inside - BUT ONLY ON VERY HIGH ACID FOODS. I am telling you this because in a real crisis, it might be useful knowledge. I do not advise it - you do it at your own risk. At a minimum I would never, ever, ever use it on any low-acid or even borderline food - pickles and acid fruit jams only. The best use for used canning lids is for jars of food that you are dehydrating and storing, or for mason jars you fill with beans and grains that aren't canned.

So what do you do? Let's say you want to make raspberry jam. You would take fresh (you really don't want to leave your stuff sitting around too long before you can it - off flavors can permeate a whole batch of something) raspberries, add sugar to taste or to meet the requirements of the brand of pectin you are using (we use low sugar pectins only because we find regular ones make a jam that is simply too sweet for us), and follow the instructions for the pectin.

In the meantime, wash your canning jars and lids carefully, and check the jars for tiny nicks on the top, because that can ruin your seal. Then submerge the jars in a pot of boiling water that comes up at least 2 inches above the top of the jars. Bring the water to a boil, and boil the jars. Meanwhile, boil the lids and rings as well. When your jam is hot and ready to be ladled in, use the jar lifter to take out the jars, and put them upside down on a clean dishtowel to drain. Then flip them, and use a ladle or spoon and the funnel to fill the jars to the recommended headspace.

Headspace is the amount of space between the food and the lid that you need to create a good seal. Often it is 1 inch, but check the recipe every time, because it may be more. When the jar is filled to the appropriate level, wipe the rim of the jar with a clean dishcloth to remove any food that might prevent a good seal, put the lid on, put the ring on (not super tightly - enough to hold the lid in place firmly), and use the jar lifter to pu the food in the canning kettle. Process for the appropriate amount of time listed for the ingredient - jams are usually 15 minutes. Processing time begins when the water returns to a rolling boil - start timing then.

When you are done, use the lifter to take the jars out of the boiling water bath, and put them carefully (don't bang them around) on a clean, dry dishtowel. You will hear a seal being formed within a few minutes - the sound is "thwuck". Some will seal right out of the kettle, others a few minutes later - this is normal. Allow the food to cool without being disturbed. When the jars are cool enough to touch, press down on the lid. If it is suctioned down and has no give, it is sealed. If you can push down on it and it pops up again, it isn't. If it isn't sealed, you can either reprocess with a new lid for the same amount of time, or you can stick it in the fridge and use that one first.

You may have been taught to can by someone who did oven canning (jars are baked), inverted the jars to create a seal, or did open kettle canning (poured hot food into jars and put on lids and let them seal themselves) these are not safe - DON'T DO IT!!!! Neither are weird things like putting an asprin (ugh!) in the jar. There have been cases of botulism with some of these methods, others could potentially cause botulism.

None of this means, however, that you can't use Mom's wonderful pickled beet recipe - you just have to use current techniques to can that old recipe.

That's really all there is to water bath canning. It is very easy, and very convenient, as long as you do it wisely.

More like this

Another category of food that usually can be canned using a water bath is chutney, if it's got enough vinegar. I use a lot more chutney in a year than I do jam.

Sharon, what is your stance on reusable lids? The ones you use with regular jars, but are two-piece (making the entire lid three piece), with a plastic lid part and rubber seal?

Like the ones sold here:


(which is in no way a plug for that site)

"Now any food with a ph lower than 4.4 (acidic) provides an environment inhospitable to botulism - which is why high acid foods can be safely pressure canned." Did you mean here that they could be safely water bath canned?

I'm also curious where you find lids in bulk. The prices I've seen online haven't been much better than buying by the box.


I believe you can't use water bath canning at my altitude (Boulder CO) because the water doesn't boil at a high enough temp. Am I wrong?

I live at 7000ft, and have had no problem with waterbath canned jams and jellies. You do have to increase your boiling time- there are plenty of charts telling you by how much for your altitude, e.g. on the pectin box, or Ball's website, or the USDA's website.

By Jesse Pino (not verified) on 06 May 2010 #permalink

You can safely use water canning with non-acidic vegetables (like cucumbers) if you add vinegar.

1M solution of vinegar has pH of 2.4 - more than enough to protect you from botulism even when diluted.

That's not a theory, we used vinegar to make canned cucumber pickles. Worked fine.

By Alex Besogonov (not verified) on 06 May 2010 #permalink

Alex, that's totally true - I'm using the broad version of the word "pickles" here - that is, any vegetable preserved in vinegar, rather than to mean just cucumber pickles. So either way, they'd be pickles.

With the multi-piece rubber lids, they are considered less than ideal - I don't teach how to use them, since they are somewhat controversial. I would only use them for high acid foods, and not anything even remotely marginal.


Also, it should be noted that high _surcose_ also prevents the growth of botulism bacteria.

So you can prepare jams which require sugar just fine.

By Alex Besogonov (not verified) on 06 May 2010 #permalink

A warning to beginners from a beginner: it's very easy to overdo the jams and pickles and very hard to do enough tomatoes!

add 2 tsp of lemon juice per pint, or 4 per quart, or the same amount of vinegar, to ensure their acidity stays below minimum levels. This might also be wise if you are canning very overripe fruit.

One quibble, just in case that tsp was a typo (though maybe your extension service sez differently) ; The NCHFP actually says 1 tablespoon bottled lemon juice per pint, and two tablespoons per quart. Bottled lemon juice is more acidic than vinegar. (surprisingly, adding it doesn't affect the flavor of your tomatoes or sauce).

NM, you are right - and I recommend the lemon juice anyway because I think it generally improves the taste. I should change my guidelines.

Alex, this is true to an extent, but not to the extent you imply. Sucrose does bind up water and reduce the risk of c.bot, but in order to be completely safe, the acidity levels must be met. Moreover, the amount of sugar you'd need to make sure there was no botulism risk would be really unpleasant.


Yes, the amount of sugar is quite great (to the extent that solution is on the brink of saturation and sometimes sugar can start crystallizing).

By Alex Besogonov (not verified) on 07 May 2010 #permalink

Great post, along with the pressure canning post.

You mentioned buying lids in bulk, would you give the link or address for your resource? It would be great to get some a bit cheaper than Wal-Mart.

Also when water bath canning, the filled jars have to be covered by at least an inch of boiling water.

OK, I'm canning dill pickles, hamburger chips to be exact, got done ready for the water bath, to "cook" them a little and all the jars already sealed, can I still water bath them????

By Kimberly White (not verified) on 23 Jul 2010 #permalink

I made some salsa. It got kind of late in the evening and I had the jars in the water bath. Fell asleep and woke up at 5 am with the jars still in the water bath boiling. they were in the water bath for almost 4 hours. All of the jars sealed when I pulled them out. Is the salsa inside still good and safe to eat?