I think the medical texts state average colon capacity is about 2qts. The standard disposable soap suds enema bags and buckets that are in use today only hold 1.5qts. That said, who is average? No one! Everyone has his or her individual capacity. And suprisingly it has nothing to do with size. I have seen tiney petite women take 2+qts without batting an eye and 250lb men start to complain after 1qt. I guess the question here, and possible variable, would be how much previous enema training the person had had. Those of us who were raised on enemas can usually really hold some serious volume.