In my twenties I came across a few E-Z-EM barium enema kits during a hospital remodel job. They were out of date and in the trash pile. I took one of them home. I should have taken all of them but I wasn't thinking strategically.
I dumped out the powdered barium, rinsed the bag out thoroughly and added it to my meager collection of enema equipment. Even once in a while I would use the bag for my enema. As I recall, it was difficult to flush out all the air from the large diameter tube, so enemas from this bag weren't too comfortable. I blamed the partially air-filled hose for the discomfort when I couldn't finish the enema. Then, for some unknown reason, I decided to measure the volume of this vinyl enema bag. Much to my surprise I discovered that it didn't hold two liters like it was marked, but instead held three quarts. I'd been trying to take a three quart enema when my capacity was a little more than two.
A year or two later I made a conscious effort to take a three quart enema and was just barely successful at it. Leading up to it was the fact that my latex douche bag was slowly stretching out from use and its capacity had expanded to two and a half quarts of solution. I used a Foley catheter for that gut-stretching enema and I thought I would burst from the pressure.
In my mid thirties I bought a black Sherema four quart bag to try taking larger enemas. After years of practice it got so I could take the full four quarts. In 2006 four quart enemas were the rule, then I tapered off. Now my capacity is seldom tested, instead I opt for nice enemas, anywhere from three to three and a half quarts of solution. A good filling without the edge play of greater volume.