Th very best, or if not the very best certainly a very, very good one, was at the Sherema Clinic in LA, almost exactly 42 years ago. I'd read about the place in an alternative newspaper as the web had not been invented at that time, and Sherema had an ad that appealed. After 'phoning for an appointment I drove to her place in (or near) Hollywood.
It was a non-descript, one floor, building with a fenced in parking area.
Upon entering the small waiting room, I was greeted by receptionist, who wanted to see my driver's license to prove I was not a cop. She then showed me a list of their services, which included enemas, colonic irrigation, B&D sessions and some other stuff, I think. I chose to receive two enemas with different nozzles.
I was then taken on a tour of the clinic and then shown into a small treatment room. The room had an exam couch on the left side with an IV stand attached to the couch at the foot end, with the bag hooks about 3 to 4 feet above the couch. Beyond the foot of the couch was a half partition wall and a toilet and sink. There was no door on the toilet area, but the partition blocked anyone from seeing someone sitting on the toilet.
The receptionist told me to get undresses and my ‘nurse’ would be in soon. I sat on the exam ouch and soon a pretty woman in very minimal undergarments came in and introduced herself and asked me about the enema volume I normally took and nozzles I'd like her to use. I told her about 2 quarts and opted for a colon tube for the first and a bulb douche nozzle for the second.
She said OK and left to prepare the enema, telling me to get undressed. I did so, keeping my undershorts on and sat on the couch. In a few minutes she returned carrying a bulging, completely filled, 4 quart red Sherema fountain syringe and hung it on an IV hook. She then told me to take off my underpants and lie on my left side as she lubed up the colon tube, which was red rubber and a Fr 32. She then spread my cheeks and slipped the tube in and started the water. Over the next few minutes, as the water flowed into me, she worked to tube up ever higher until pretty much the whole about 40 or 50 inches was fully into me.
Amazingly, she got that whole bag full of soapy water into me and i got up and quickly got onto the toilet without leaking anything and started to poo and poo.
After I was done, or so I thought, on the toilet, it was back to the exam table for the rinse enema, which was the same bag full but given back ;lying with a bulb douche syringe connected to the enema hose. I pood this out sand dressed and left and went to a nearby adult book store.
While in the store, the massive enema kicked in again, and I had to use their bathroom.