Let's lay this whole ". ..colon becomes dependent on them..." myth to rest once and for all. I have taken enemas for close to forty years. At times I have taken numerous enemas daily for several months at a time. When I stopped, for a period of time, there was absolutely NO change in my bowel habits, NONE, NADA ZILTCH!!!!! You may become psychologically addicted but not physically.
Adding salt to the water to make it isotonic will eliminate the danger of water imbalance. Use one teaspoon salt per quart of water.
I have to address the comment about "acquired megacolon." The so called megacolon is a natural occurrence in some people who have one or two extra loops in their sigmoid colons. It is genetic and occurs because of extra length not diameter. Taking large volume enemas DOES NOT STRETCH YOUR COLON!!!!! You cannot acquire something that is genetic.