Not enough childhood enemas for the question to be relevant, but now, I certainly do. What I feel depends on how the enema is given. If I have a shower enema, the feelings are intense, due to the water surging in under pressure (yes, I'm careful). If I do a low enema with the Higginson, again it's the surging of the water, plus warmth. If I do a bag enema, it's the insertion (much larger / longer nozzle), plus the water flowing in, plus the heat, and finally the feeling of pressure & discomfort, separate from any cramps, that tells me the water has reached my ileocecal valve. That's the feeling I wait for. It tells me my colon is full. I keep hoping that valve will open, and allow an even higher cleansing, as @azdiane has mentioned, but so far no. As far as when I give, it's a question I don't normally ask. The woman's reactions (gasping, “Omigod” “Please, I can't take any more,” whimpering, moaning, groaning, plus the water dropping in the bag or can, tells me. That said, I do close the clamp to allow her colon to relax, or lower the bag or can when she needs a break. OTOH, I have never had a girl fail to take at least 2 quarts. Normally, she must empty the bag. I have on occasion chosen to give a smaller amount as a first enema, to relieve some of the pressure associated with the feces stopping up her colon, but the second (and 3rd) enemas always are at least 2 quarts, more if she can take more. I use the “no more will go in” system when I give the second & third, but with the height of the bag or can above her anus no more than 24 inches. It's almost always possible to give more, but many small women cannot take much more…