Personally, at home I use warmed bottled spring water for my enemas. But RO water is fine, and I think you will find that you will experience a more comfortable enema and achieve a more thorough elimination if you mix Sea Salt with it.
The temperature should be just a bit above normal body temperature, and I suggest using a bath thermometer at preparation time to insure the water is between 102-103 degrees F, but no more.
An enema should, and can be a pleasant refreshing and relaxing experience. Try to insure that you have a convenient area to prepare it, and a comfortable place to take it. I know that's not always easy, depending on your situation at the moment, but as you gain more experience it will eventually come naturally.