Hi - I thought I would recount my experiences with one of the yoga cleanses, called basti (or sometimes vasti, of jala basti). It is a method of giving yourself an enema without a bag. Maybe it is worth my mentioning it, because some of the web literature is a bit obsure (' find a river with clean water...').
I learn this from a book called 'Hatha Yoga', by Theos Bernard.
A pre-requisite is to be able to do nauli - this is where you isolate the central abdominal muscles into a ridge (you can see this on youtube, etc). This can take around a month to learn, doing 5 mins per day, and is beneficial in itself.
So... basti. You insert a short enema nozzle, and need to be able to squat or kneel so that the end of the tube is in water. It depends on you - it might work in a bath, or with a a pan of water on the floor.
When you do central nauli (not the rotations) very strongly, it creates a vacuum, and sucks water in. After a few of these, take the tube out, do some yoga postures to massage, the abdomen, and expel as normal.
So, is it any good? This is hard to assess - it is really intended for very serious hatha yogis, who are eating a restricted diet. Personally, I think that it is difficult to take in much water, because the act of doing nauli itself compresses the abdomen, and taking in much more than a pint is unlikely.
I welcome any other views (and can provide more info if needed).