I use 1 teaspoon of soap to 2 quarts of water. I also double up when very constipated.
Not doing a rinsing enema, I don’t believe, causes any serious physical damage to the intestines but can leave you with irritated bowels for 1 to 2 days. In the past, say 50-60 years ago, rinsing enemas were not commonly given and no permanent damage seemed to have ensued.