I would incorporate all of Switchablesusie's comments and add that I'm not a medical expert, but I can say from experience, that enemas have served me well for a lifetime. I've also done extensive research and read most anything pertinent to the use of enemas for medical, health or personal/psychological benefit.
Enemas were a common therapeutic treatment in the past. This is confirmed in medical/nursing texts for well over a hundred years. Many doctors, or other experts, advocated their use and effectiveness for many different circumstances. Google Books is a great resource for any historical data and information.
While frequency of use, and type of solutions, is often debated and encouraged or discouraged, the end result is never changing. We must eliminate waste one way or another.
I wanted some assurance that I wasn't intentionally harming myself. Aside from some concerns about my psychological status, especially when fairly young, I can say that I believe from experience that my enema use has been quite beneficial from a healthy perspective. An enema often precludes the need to consume other digestive aids or drugs. My PSA levels are excellent and my family history of various issues hasn't smitten me yet. All in all, this simple procedure seems to have provided many physical benefits. I try not to overuse them, however.
As far as those pesky psychological issues, I have come to terms with this particular quirk or kink. Sites like this, the internet, and general information, have been very beneficial over the past few decades. I finally discovered I wasn't the most screwed up or weird one around. In fact, I can just enjoy the simple procedure for what it is. My equipment fetish provides some other enjoyment just as other "hobbies" do it for other people.
I'm not sure that these are necessarily "GOOD" answers, but using enemas in a safe and sane manner, with solutions that are medically common or proven, and with reasonable frequency, shouldn't cause harm and may have many beneficial results. My routine physicals and test procedures have never demonstrated any ill effects.