That is what I have been wondering about. I used a four quart stainless steel pan and packed it full. Then I boiled it down to about an inch in the bottom of the pan.
I had both organic apple cider vinegar and distilled apple cider vinegar and diluted batches with both, but threw out those batches because I could not stand the taste.
Then I went to the store, I think it was Walmart in Tucson, and bought a bottle of vodka. That was when I started boiling the mixture further down after reading something about that on here. Even with the stronger mix, I can take the vodka batches but no more than 3/4 teaspoon twice a day. Otherwise things get out of control.