Do I need to pressure can green beans or will a boiling water canner work just as well?

Notice that the last instruction above is different from the usual boiling water bath instructions. For regular boiling water bath canning in an open pot you must cover the jars completely with 1 - 2 inches of water above the lids. When you use a pressure canner as a boiling water bath, the water only comes up to the shoulders of the jars. Screw or clamp on the lid of the pressure canner and leave the vent, or petcock, open. Turn on the stove to high heat. When steam starts coming out of the vent vigorously, start timing your boiling water bath processing time according to the instructions in the recipe for whatever you are canning.

While I know a couple of older women who use a water bath canner for green beans it is really not safe. Older people who have done things the way they were taught long ago often won't change their ways no matter what. Though there are only an average of 10 cases of botulism due to home canning around the world each year you don't want to be one of the ten.